[macOS] Add input action (CMD + W) to close dialogs.

[bruvzg]

Fixes #86200 and partially #109007.

[passivestar]

alternative to #107303, but why #ifdef instead of .macos override like in all other bindings?

[Ivorforce]

This is not a fully accurate representation of these macOS shortcuts. In applications with tabs, these are the shortcuts:

In other words, I would perhaps rather expect the existing "Close Scene" (cmd w) shortcut to also close windows when there is no scene open, or the current window does not have tabs / scenes. (instead of adding a new action)
A "close window" shortcut (cmd shift w), in Godot, would probably be more akin to "close project".

[bruvzg]

Closing in favor of #107303