Fixes #3073: Adds Bar as a replacement for StatusBar

[tig]

Fixes

• Fixes Create a new Bar view to replace StatusBar (and eventually MenuBar) #3073
• Fixes StatusBar should support right alignment on last StatusItem #2106
• Fixes Menu hints in StatusBar #191

Todos

Still very much a Proof of Concept/Prototype

• Implement Shortcut view that holds a Key, KeyBindingScope, Title, and help Text.
  • Renders just like a MenuItem.
    • Proper spacing/alignment of help text.
  • Supports arbitrary Views in the CommandView (first) position. E.g. CheckBox
  • Works with KeyBindingScope.Application and KeyBindingScope.HotKey.
  • Supports mouse clicks to activate the shortcut
• Implement Bar view that
  • Looks just like the old StatusBar (StatusBarStyle = true, Orientation.Horizontal)
  • Looks just like the old MenuBar (StatusBarStyle = false, Orientation.Horizontal)
  • Looks just like the old Menu (StatusBarStyle = false, Orientation.Vertcal)
• Update UI Catalog to use the new Bar
• Replace Toplevel.StatusBar

Pull Request checklist:

• I've named my PR in the form of "Fixes #issue. Terse description."
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• 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