[Feature]: Move Color Mode out of Experimental and add a easy theme switcher

[joshyorko]

Before submitting

• I have searched existing issues and discussions to confirm this hasn't been requested

Problem or motivation

Move the color mode out of experimental and add a real theme switcher easily acceible

Proposed solution

Move the color mode out of experimental and add a real theme switcher easily acceible

Alternatives considered

No response

Area

Desktop app

Acceptance criteria

Enable theme switching from any DevPod Desktop app view

Additional context

No response