vscode: Show notification when upgrade is available

In case the window location path changes. Not entirely sure if it can
but best to be on the safe side.

See #2359

Closes #1652
Closes #2221

And link to the release notes.

vscode: Customize welcome page for code-server

- Title/subtitle are now code-server and VS Code version
- Added a list of code-server help links

See https://github.com/cdr/code-server/issues/2328

The new fields are from vscodium and make the welcome page
documentation links work correctly.

I also renamed the distribution to "code-server" so that when you're
in a browser, it now says code-server instead of Code OSS.

Use file system for user data

This is included in the bundle now.

It's possible that using browser storage makes more sense with settings
sync, so we might want to revisit this once/if we get settings sync
working. As it currently is though, browser storage just causes jank.

The path was also missing a `User` at the end so I added that. This
might affect the Vim extension which would have been writing to the
wrong path previously but I don't believe it should affect anything
else since they would have been writing to browser storage.

- Fixes #2208
- Fixes #2231
- Fixes #2279
- Fixes #2274

v3.7.2

Update VS Code to 1.51.1

This is the last unused variable in the create terminal payload.

This makes it re-connect automatically.

It works, at least, but there are still some missing parts.

The telemetry service depends on this now. I had to move it into
invokeFunction and use accessor.get otherwise getLogger on the service
was undefined.

I also had to move some the extension management service because it
depends on the moved telemetry service. I moved a few other services as
well to better match VS Code (sharedProcessMain.ts).

I swapped some this.services.get with accessor.get since that seems to
be the correct method although for these other services either method
seems to work.

login.css: Disable webkit appearance for input elements 

Separate process wrappers and pass arguments

I removed this under the impression the default was to allow it anywhere
but that's not the case. Since the service worker was already registered
in my browser I never got the error during testing.

Fix 404 webviews and tar endpoint

Not sure why Safari does these things...

Closes #2247

This reverts commit f79bb210.

It was checking the request path but for tars the path is in the query
variable so the request path is irrelevant.

An extra slash caused a 404 (was /webview//vscode-resource).