Copilot-based TS refactors

[sandersn]

This PR adds copilot suggestions to various Typescript refactors and quickfixes. It also adds a separate quickfix for implicit any that lets Copilot infer types from the body of a function, which is less context than the TS codefix. However, it creates new interfaces with reasonable names and uses them where appropriate, which the TS codefix cannot.

The existing refactor/quickfixes are followed by Copilot's inline chat now:

• Extract to X now asks copilot to provide a name for the new constant/function/type instead of showing the rename UI.
• Implement X now asks copilot to provide reasonable implementations for inherited interface or abstract methods. This replaces the TS-generated throw new Error("Not implemented").

I think the the UX and performance are both good enough for insider use at this point, so I think it's worth merging behind the typescript.experimental.aiQuickFix flag.

Some future work:

• Could the codefix could be skipped if there are lots of types around already?
• Could the codefix prompt by modified to omit "Please generate new interfaces" if there lots of interfaces already declared?
• Fix code formatting!

Extends #190690

Question and work from that PR that are now resolved:

• Infer from types now works in JS files.
• When given enough context, inline chat works well, especially since it will edit code if the AI produces a code sample. I tried showing multiple name suggestions in the chat panel, but I felt like it didn't add enough utility -- and the suggestions were usually all good or all bad, so taking the first suggestion works well enough.

[sandersn]

@mjbvz and @jrieken can you take a look at this?

[jrieken]

@sandersn There are some eslint failures. You can see them when running yarn eslint (actually the precommit hooks should have reported them...)

I wonder if we should grow the typescript.experimental.aiQuickFix setting, e.g this isn't just quick fixes anymore and also more nuanced. Maybe a new setting like typescript.exprimental.aiCodeActions which value is a complex object would be best, e.g each key would correspond to a feature

[sandersn]

Ah, that's right. I completely messed up the setup of vscode's formatter, so I skipped the precommit hook. I'll go back and figure that out so the machine can fix the formatting for me.

Edit: I didn't know about typescript.enable.format, but somehow set it to false in the past. Makes it very hard to format documents with it.

[sandersn]

OK, I added a more complex options object. If you just create the top-level object as {}, all the code actions are enabled. Then you can set individual ones to false.

I don't know if this is the usual way to do it, so please let me know if there's a standard I should follow.

[sandersn]

I realised that the config still effectively defaulted to true, and that the altered descriptions weren't working.
I fixed that and also created custom descriptions, so please take a look at those for wording.

[sandersn]

Linux smoke test case failed:
1) verifies that auto save triggers on shutdown

But I don't see how that could be related to my change.

[jrieken]

Merging caused a build failure down the line (when doing the product build...) A revert PR is up (#193810) and this needs to be reopened and looked at again

[sandersn]

How can I see the build failure?