Fixes #3029 - Refactors MouseEvent and APIs to simplify and make consistent

[tig]

Dependent on

• Fixes #3793. Simplifies and makes correct KeyDown/Up API, Fixes: CollectionNavigator should be called on KeyDown #3795

Fixes

• Fixes Refactor MouseEvent and MouseEventEventArgs to simplify #3029

Proposed Changes/Todos

• Clean up Application.Mouse.cs
• Clean up View.Mouse.cs
• Merge MouseEvent and MouseEventEventArgs into MouseEventArgs
• Update API docs/conceptual docs

What this does NOT fix

• Command is too tightly coupled with KeyBindings #3778
• HighlightOnPress and/or WantContinousButtonPressed has issues with nested subviews. #3753
• Mouse doubleclick stops continous pressed events. #3404
• Mouse API makes it way too hard to track button pressed #3312
• ProcessButtonClick strips any modifier keys from mouse events #2588

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
• My code follows the style guidelines of Terminal.Gui - if you use Visual Studio, hit CTRL-K-D to automatically reformat your files before committing.
• My code follows the Terminal.Gui library design guidelines
• I ran dotnet test before commit
• I have made corresponding changes to the API documentation (using /// style comments)
• My changes generate no new warnings
• I have checked my code and corrected any poor grammar or misspellings
• I conducted basic QA to assure all features are working