Add Action to Copy Objective-C Selector Name of @objc Swift Method

[CodaFi]

Description

When a Swift class is marked @objcMembers or it has Objective-C/@objc ancestry and @objc methods without visible selector names, the Swift compiler applies a pretty complex set of heuristics to produce a readable Objective-C selector name. We should provide an action to run the compiler’s Objective-C selector mapping logic and copy the selector name for a Swift method to the pasteboard.

[CodaFi]

Maybe not a starter bug, but a good medium-sized vertically-integrated set of medium-difficulty patches. This may require light compiler refactoring, a new sourcekit request, and LSP plumbing.