Merge #11481

Merge #11481

11481: Display parameter names when hovering over a function pointer r=Veykril a=Vannevelj

Implements #11474

The idea is pretty straightforward: previously we constructed the hover based on just the parameter types, now we pass in the parameter names as well. I went for a quick-hit approach here but I expect someone will be able to point me to a better way of resolving the identifier.

I haven't figured out yet how to actually run my rust-analyzer locally so I can see it in action but the unit test indicates it should work.

Co-authored-by: Jeroen Vannevel <jer_vannevel@outlook.com>