See gh-23884

- Add maxInMemorySize property to Decoder and HttpMessageReader
  implementations that aggregate input to trigger
  DataBufferLimitException when reached.

- For codecs that call DataBufferUtils#join, there is now an overloaded
  variant with a maxInMemorySize extra argument. Internally, a custom
  LimitedDataBufferList is used to count and enforce the limit.

- Jackson2Tokenizer and XmlEventDecoder support those limits per
  streamed JSON object.

- Configurable limits for multipart requests with Synchronoss NIO.

- Centralized maxInMemorySize exposed via CodecConfigurer along with
  ability to plug in an instance of MultipartHttpMessageWrite.

Closes gh-23884

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* [ ] http://www.apache.org/licenses/ with 1 occurrences migrated to:
  https://www.apache.org/licenses/ ([https](https://www.apache.org/licenses/) result 200).
* [ ] http://www.apache.org/licenses/LICENSE-2.0 with 6515 occurrences migrated to:
  https://www.apache.org/licenses/LICENSE-2.0 ([https](https://www.apache.org/licenses/LICENSE-2.0) result 200).

Issue: SPR-17388

Includes nullability declarations for the protobuf package.

Issue: SPR-15776

This commit introduces Protobuf support in WebFlux via dedicated
codecs.

Flux<Message> are serialized/deserialized using delimited Protobuf
messages with the size of each message specified before the message
itself. In that case, a "delimited=true" parameter is added to the
content type.

Mono<Message> are expected to use regular Protobuf message
format (without the size prepended before the message).

Related HttpMessageReader/Writer are automatically registered when the
"com.google.protobuf:protobuf-java" library is detected in the classpath,
and can be customized easily if needed via CodecConfigurer, for example
to specify protocol extensions via the ExtensionRegistry based
constructors.

Both "application/x-protobuf" and "application/octet-stream" mime types
are supported.

Issue: SPR-15776

Issue: SPR-17029

Issue: SPR-16898

Functionally equivalent updates to package private classes to improve
the code and make it easier to understand.

Includes redeclaration of CodecConfigurer.DefaultCodecs without concrete Jackson decoder/encoder references in order to avoid hard Jackson dependency.

Issue: SPR-16064

This binary format more efficient than JSON should be useful for server
to server communication, for example in micro-services use cases.

Issue: SPR-15424

Simplify the internals of the DefaultCodecs implementation favoring
explicit fields per override vs a generic list of readers and writers
for overrides.

Essentially drop "Configurer" suffix from nested interfaces.

Issue: SPR-15515

This commit refactors the CodecConfigurer, with it's subtypes
ServerCodecConfigurer and ClientCodecConfigurerTests, into interfaces
instead of classes.