iTermHotKeyController.m

Fix a bug where hotkey windows appearing in a different display than the currently key window (in another app) would not receive focus and would forget which app was previously active. Issue 6353

The two key changes are
1. Add a method to activate the app with a completion block
2. Don't throw away the existing previous state when a non hotkey window becomes key during a rollin. The logic already existed for a rollout.
Here's what would happen:

rollInAnimated
  [NSApp activateIgnoringOtherApps:YES]
  rollInAnimatingInDirection:
(if there's no animation, the rollin finishes immediately)
App becomes active
A non-hotkey window becomes key

Now, here's what happens:

rollInAnimated
  [NSApp activateIgnoringOtherApps:YES]
App becomes active
A non-hotkey window becomes key, but it's ignored because there's a roll-in in progress
rollInAnimatingInDirection:
(if there's no animation, the rollin finishes immediately)