Improve C# method listing

[paulloz]

This is mainly a PR for 3.x.
Fixes several issues with animation's method tracks and C# scripts:

• methods from base classes not being listed
  • Missing inherited methods in the "Select Method" window for animation call method tracks for C# scripts. #46408
• error messages when selecting a method from the list
  • AnimationPlayer Call Method Track not being able to select C# custom function from editor #39156
  • Animation Player Keyframe callback track doesn't allow setting a callback from attached script unless script has same name as AnimationPlayer node using C# #37803

Cheers.

Bugsquad edit: Fixes #46408, #39156, #37803.

[neikeq]

Thanks!

[akien-mga]

Cherry-picked for 3.4.