I recently noticed that on my Windows 11 machine, Zed no longer receive
the `WM_DWMCOLORIZATIONCOLORCHANGED` message when the system theme
changes. This functionality was present in the past. While this change
might be unexpected, it's understandable given Microsoft's history of
system updates.

This pull request proposes an alternative approach using the
`WM_SETTINGCHANGE` message to handle theme changes.

Release Notes:

- N/A