Modernize Menu - Base on Bar and address litany of issues

[tig]

Related to:

• Refactor KeyEvent and KeyEventEventArgs to simplify #2926
• Create a new Bar view to replace StatusBar (and eventually MenuBar) #3073

Todo:

• Menu should use Frame instead of DrawFrame #2539
• Enable using MenuBar as an alternative for ComboBox #2404
• MenuBar: Support Title so that a Window (with wasteful border) is not needed to show app title #2108
• Update constructors to add Commands and AddKeyBindings instead of using shortcut and action.
• Update ProcessKey/OnKeyPressed handlers
• Do not allow HotKeys to invoke a menu item if it is not visible. Shotcuts yes, hotkeys no. Terminal.Gui v2.x - Planning & Debate Thread #1940 (reply in thread)
• Double check that we have sufficient Unit Tests and add any obvious missing tests that will verify we don't lose functionality.
• Shortcut should be Key based, not KeyCode -
• Hotkey should be Key based, not Rune

Originally posted by @tig in #2974 (reply in thread)

[tig]

Progress on this was made in #3073. Specifically:

• I developed Shortcut and Bar sufficiently that I'm confident they can be used as a basis.
• Formatting/Layout in Shortcut and Bar support the current look & feel of both MenuBar and Menu
• I introduced two temporary classes: Menuv2 and MenuBarv2 that are a starting point.