Add references support for instance variables

[monkeyWzr]

Motivation

Closes #2641

Implementation

Add references support for instance variables.

Manual Tests

[monkeyWzr]

I have signed the CLA!

[github-actions]

This pull request is being marked as stale because there was no activity in the last 2 months

[vinistock]

This looks and we can ship. For some reason though, CI seems to be stuck and won't run. I also can't seem to trigger it manually for whatever reason. Could you please try rebasing this branch to trigger CI again?

Regarding the discussion in the issue, ideally we would use our type inferrer to narrow instance variable references only to the ones that actually refer to the same one. Would you be interested in tackling that in another PR? If not, I'll create an issue for it.

We'd essentially need to require the type inferrer to be passed to the references finder and then we need to ensure that the receiver type of the instance variables match the one the user clicked on.

[monkeyWzr]

@vinistock

Regarding the discussion in the issue, ideally we would use our type inferrer to narrow instance variable references only to the ones that actually refer to the same one. Would you be interested in tackling that in another PR? If not, I'll create an issue for it.

Yeah I'd love to give it a shot!