Add ability to detach the timeline editor window

[Crystalwarrior]

There's already a plugin that does this for the script editor which we could use as reference
https://github.com/LaoDie1/godot-float-script-editor

[AnidemDex]

Relevant PR godotengine/godot#62378

[AnidemDex]

That PR was merged, we can follow a similar behavior