Disable some actions in secondary window

[jeremypw]

Based on #1624

Limit certain behaviour that would be complicated to synchronize/reconcile with the primary window.

• Access to terminal
• Change active project (ChooseProjectButton)
• Change active project (context menu)
• Clone repository
• Checkout/create branch

[danirabbit]

I don't like this at all :( We should definitely make active project per window for example

[jeremypw]

@danirabbit Funnily enough I came to the same conclusion and am implementing that now. It should be possible to allow most actions to be done in either window but I do not want to start saving state per window atm so there may be some restrictions.

I envisage being able to work on two different projects without restrictions but I think we will have to avoid having the same active project in both windows unless git actions are disabled in one of them.

[jeremypw]

I think I'll close this and submit a more limited PR implementing per-window active project, based on #1574 as that touches the same code.

Then we can think about any necessary limitations as and when specific issues arise.