Convert SetSelectedMethodMessage to include multiple modeled methods

[koesie10]

This converts the SetSelectedMethodMessage to include multiple methods. It also adds a new message to replicate the SetModeledMethodMessage with multiple modeled methods so that all state is now pushed through correctly from the modeled method view provider. Unfortunately, the name SetModeledMethodsMessage is already taken by the modeled methods map, so I've created a new message SetMultipleModeledMethodsMessage. We may want to consider changing these once all messages are properly renamed.

The changes to canMethodBeModeled are directly copied from https://github.com/github/vscode-codeql/pull/2942/files#diff-fb5d586d735e8d18fcae2a4225ba24aff4416e9423ea1a4fb1af7bc5d5805da8

Checklist

• CHANGELOG.md has been updated to incorporate all user visible changes made by this pull request.
• Issues have been created for any UI or other user-facing changes made by this pull request.
• [Maintainers only] If this pull request makes user-facing changes that require documentation changes, open a corresponding docs pull request in the github/codeql repo and add the ready-for-doc-review label there.

[robertbrignull]

LGTM

[robertbrignull]

Did we discuss including methodSignature: string; in this message, so you don't have to work out the signature by looking at the modeled methods?

That would also make it easier to remove all modeled methods for a method signature, instead of having to set it to the array containing one element with type: "none".

I'm happy for you to make this change in this PR or I can do it in a followup, because I'll be using this message in my next PR.

[koesie10]

It does make sense to add it here. Right now, this message is only used for communication from the extension host to the view, but we'll definitely need the signature for the communication from the view to the extension host. I'll change the message now so that I can also use it in a follow-up PR (after #2924).

[robertbrignull]

Thanks for updating and adding methodSignatures.

Has conflicts, but otherwise LGTM