Test RenameProvider api extensions

[jrieken]

Refs: #7340

• any @octref
• any @mjbvz

Complexity: 2

Note that until e56aced ships with insiders you need to enable proposed-api for your test extension.

We have added a new, optional, method to the RenameProvider, namely: resolveRenameLocation. Understand what it does and implement an extension that uses this.

[jrieken]

FYI - to test against the latest API do the following:

• open your extensions package.json file
• change the engine.vscode property to *
• run npm run postinstall (assuming you have the vscode module as dev-dependency)
• undo the engine-version change from step 2

[mjbvz]

Blocked on testing by #48592

[mjbvz]

@jrieken implementation of design looks good in my testing but @octref and I were confused by how range is used in the api design. I believe we'd like to discuss this at the API sync