Customize app expose settings

[rogerluan]

Describe the Pull request
This PR replaces the app exposé boolean settings that weren't ideal, with a dropdown menu that lets you choose between "always" show the app exposé, "never", or "if needed", which shows if there's more than 1 window.

By the way I also improved the autolayout a little bit. It was kinda messy imho 😅

Screenshots

Fixes
#206

Pull request type
Keep only the option that better matches your pull request.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Tested?

I did test myself all the 3 behaviors. Manual/exploratory test, no unit tests.

Test Configuration:

Checklist
Use this list to keep track of your progress:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

No tests were written, as there're no related tests to similar parts of the app either 🤔

[rogerluan]

@pigigaldi can we get this merged and released? :)