fix reconnection of native language servers

[akosyakov]

What it does

fix #6200:

• Force restart language client contribution on reconnect: Since restart skips if a server is not running, on reconnection a server has to be restarted forcefully if it was running before.
• Don't wait when a stopped json language server is ready: Timing of resolving LanguageClient.onReady promise is changed in never version of vscode-languageclient. It could lead to a situation that clients still use onReady of a language client before reconnection.

How to test

• cause connection issues either with system proxy or by stopping a server
• make sure that json language server is running after reconnection and proper configuration snippets are available in launch.json
• make sure that other native language servers are restarted on reconnect as well, for example for typescript

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[akosyakov]

@tom-shan Could you try whether it resolves #6200?

[tom-shan]

@tom-shan Could you try whether it resolves #6200?

I'm veryfying it

[svenefftinge]

I've tested reconnection with json and typescript, as well as changing JSON schema through preferences. Everything worked nicely!

[tom-shan]

When follow the reproduction steps in #6200, the suggestions are always right. So I think #6200 is resolved. I will pay attention to this problem in my bad network and check whether the problem is gone.