gpui: Implement dynamic window control elements (#30828)

Allows setting element as window control elements which consist of
`Drag`, `Close`, `Max`, or `Min`. This allows you to implement
dynamically sized elements that control the platform window, this is
used for areas such as the title bar. Currently only implemented for
Windows.

Release Notes:

- N/A
ca3f46588aMatin Aniss committed on 6/6/2025, 5:11:24 PM· committed by GitHubparentd9efa28
11 files changedLine totals unavailable