* Add Istio control plane otel MAL expressions and UI template
* Remove OpenCensus receiver, add OpenTelemetry receiver
* Transfer oc receiver to ot receiver
* Create indices on boot
* Document istio metrics and otel receiver
* Update CHANGES.md
* Fix potential NPE
* Add group to meter and cleanup istio mixer
* Update e2e case due to the change of meter metric name
* Update prometheus fetcher config, fix sql builder issue of h2
* Disable istio and so11y metrics by default.
* Fix micrometer testcase

Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

* Add v8 upgrade document and fix some tiny doc issues.

* Add link to STAM paper.

Here are the basic and simple usages of the MeterSystem APIs.

## Meter Creation
New meter could be created based on metrics name, function, scope and data type. 
1. Metrics name is still the storage entity name.
2. Functions are every similar with the OAL function, just accepting different input.
```java
final MeterSystem meterSystem = MeterSystem.meterSystem(getManager());
meterSystem.create("test_long_metrics", "avg", ScopeType.SERVICE, Long.class);
```
NOTICE, this creation should only be called in the `module#prepare` stage, otherwise, `Can't create new metrics anymore` exception will be raised after the **CORE** module `start` stage finished. You may find out, there is a chance `create` could be executed successfully in your own `module#start` stage, but it it just because of the sequence of provider loaded by the class loader, **no guarantee, so please don't do that**.

## Runtime Calculation
`AcceptableValue` is the object created at the runtime to accept new metrics value.
```java
         final MeterSystem service = getManager().find(CoreModule.NAME).provider().getService(MeterSystem.class);
        Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                final AcceptableValue<Long> value = service.buildMetrics("test_long_metrics", Long.class);
                value.accept(MeterEntity.newService("abc"), 5L);
                value.setTimeBucket(TimeBucket.getMinuteTimeBucket(System.currentTimeMillis()));
                service.doStreamingCalculation(value);
            }
        }, 2, 2, TimeUnit.SECONDS);
```

## Meter Functions
Right now, only `avg` function has been implemented. I submit this PR as soon as possible to get your feedback. I will add more functions.

## Notice
1. Make slow trace query available in the sampled record. Logically, they are the same thing. The UI doesn't need to concern about the trace as a special case.
2. Endpoint dependency will be removed from the dashboard. Because no query available for it. We will provide a new page for that in 8.1
3. Comparison page will be removed due to dashboard is powerful enough to replace it.

Here are the list of changes we made in this pull request. Top 3 are the principle changes, others are following these principles.
1. New agent and mesh report protocol. 
2. New agent header protocol. 
3. Service register, instance register and network address register have been removed permanently.
4. Service traffic, instance traffic and network alias metrics are added to replace the service, instance and network address inventory.
5. Register process has been removed.
6. Metrics stream process supports insert only mode, especially for traffic entities.
7. Metrics stream process supports no-downsampling mode for traffic entities and network alias.
8. Remove all register mechanism and cache in the java agent.
9. Remove MONTH step in GraphQL query.
10. Update UI to remove MONTH step query, the max query range is 60 days now.
11. Simplify the TTL to metrics and record. And the unit has been formatted in Day unit. No specific TTL for ElasticSearch storage.
12. Buffer mechanism of trace receiver and mesh receiver has been removed due to no register.
13. New service id, instance id and endpoint id rules, including service relation, instance relation and endpoint relation id rules.
14. Java agent support `keep tracing` mode, meaning, agent generating tracing context even the backend is unconnected/unavailable.
15. Plugin test tool up to date, in order to support new protocol.
16. Plugin tests expected data files updated.
17. E2E tests updated.
18. Telemetry of Grafana config has been merged into one.
19. Documentation updates.
20. [TBD] InfluxDB storage implementation is not available, need @dmsolr to fix later, in order to reduce the master change block by this PR.

* Provide profile task downstream to sniffer

* fix agent unit testcase issue

* add profile switch config on sniffer

* fix es error

* 1. add @DefaultImplementor on the sniffer profile task service
2. change ProfileTaskExecutionService#PROFILE_TASK_READY_SCHEDULE to final and remove volatile
2. fix style error

* change timeFromStartMills use `<` to compare

* 1. add `maxSamplingCount` to profile task
2. make profile task limit to the common package

* 1. change `agent.active_profile` to `profile.active` and make true on default
2. add `maxSamplingCount` in profile task
3. use `createTime` to check has new command list
4. add task re-check before process profile task

* 1. add `profile-receiver` document
2. change `ProfileTaskExecutionService` use single schedule thread pool
3. cache dont need fetch data when no data, use auto-fresh mechanism only

* remove navigate time judge, fix comment wrong meaning

* Add ALS proto and receiver in envoy

* Rename metric to metrics.

* Fixed test case execute failure issues.

* Make Jaeger receiver works in 12450 as default.

* Finish compile and codebase.

* Make codes runnable.

* Finish Jaeger query tests.

* Add document for jaeger receiver.

* Add readme.

* Fix a break link.

* Finish doc.

* Codebase for zipkin span persistence.

* Fix missing fields in storage.

* Miss the latency field.

* Finish some tests.

* Fix wrong latency.

* Finish doc and reset application.yml

* Make the description more clear.

* Extend envoy metric service, scope and OAL lexer/parser.

* Finish metric extension and oal.

* Make test env works.

* Finish test of envoy connection and memory metric.

* Change document.

* Finish docker compose test.

* Support sampling trace at server side and keep metric right.

* Add a trace sampling document

* Fix wrong default value.

* Fix document issue.

* Fix assemble issue.

* Fix wrong settings and doc.

* Change some codes to make zipkin receiver works, not done yet.

* @adriancole Zipkin receiver is coming back again.

* Fix document and fix for Zipkin receiver.

* Fix some bugs.

* Fix register bug.

* Fix transfer bug for new backend core.

* Add more documents for v6.

* Make default setting consistent .

* Change oal doc.

* Remove typo

* Remove document WIP tag.

* Fix few words.

* no message

* Adjust contribution guides.