Made ColorSelector fully functional: added onPress handling, save buttons for the thread color, and modified the ColorPickerModal height to fit the smaller size of ColorSelector (as opposed to ColorPicker).
Full context in Linear issue. Phasing out ColorPicker can be handled in a future diff. Depends on D3868.
I thought putting an invariant here was a reasonable trade-off vs. refactoring the types in the fullStateSyncActionType payload (specifically StateSyncFullActionPayload which is derived from ClientFullStateSync which is derived from BaseFullStateSync) which are used across clients and keyserver.
Open to re-exploring if that would be preferred.