Avoid overriding the start function of Client

[st0012]

Motivation

It turns out that the sendRequest function always calls the start function of the client. So everything we put in the overriding function will be called multiple times just during the initialization of the extension.

While we currently only set the formatter and the server version in the overriding function, which are fine when getting called multiple times, it sets a dangerous precedent. For example, if we put another sendRequest call in it, then it'd create an infinite loop.

Implementation

Add a updateStatesFromInitializationResult function to Client that should be called manually by a Workspace after it called Client#start.

Automated Tests

Manual Tests

[vinistock]

I'm not sure this PR is handling the underlying issue. We don't want the client to be started by anything other than the Workspace. Can we instead try to guarantee that the dependency tree is not accidentally trying to start the client?

[st0012]

Given that other APIs like sendNotification or sendProgress also force starts the client, it seems to be an expected behaviour. If we look at the implementation of client.start, it uses state check to avoid repeated starts anyway.
So I don't think having client.start called outside of workspace is a problem.

[vinistock]

If we look at the implementation of client.start

Oh, you found the promise I was trying to find in the code. Perfect, yeah if it's guaranteed to not fire multiple promises, then it should be fine 👍