CommandBar-related Controls Should Not Use AppBar Prefix

[robloo]

Describe the bug

I would classify this as an obsolete API being released as new -- so it's a kind of API bug.

WinRT (Windows 8 timeframe) originally had an AppBar control. That came along with a family of controls such as AppBarButton, AppBarSeparator, AppBarToggleButton, etc.

For a number of reasons UWP then deprecated AppBar replacing it with CommandBar. However, the child controls were not renamed to preserve compatiblity.

We are carrying-over the CommandBar control now in Avalonia... however, we are also carrying over the obsolete AppBar... terminology. All of this terminology should instead be CommandBar... as there are no plans to ever release an AppBar control.

To Reproduce

See the new CommandBar controls API:

https://github.com/AvaloniaUI/Avalonia/tree/master/src/Avalonia.Controls/CommandBar

Expected behavior

New Avalonia controls should not be using obsolete WinUI terminology from the start.

Avalonia version

12.0 rc1

OS

No response

Additional context

No response

[robloo]

cc @MrJul @jsuarezruiz As any fix here would need to be done ASAP...

[rabbitism]

#20875