Add some form of onboarding

[waydabber]

An onboarding is needed to give a brief overview of the functionality of the app.

Display control features and apple keyboard hooking should have an explicit allow/disallow switch on the onboarding screen with special care for upgraders from the v1.1.x version so the feature could be opt-in for them to avoid confusion.

[waydabber]

Onboarding will be tied into the new app menu - #1880

[waydabber]

Onboarding will be super simple (for now) as a proper tutorial would be so complex that it would defeat the purpose.

These things will be implemented:

• Upon first launch the app menu will automatically open
• An arrow pointing to the menu bar icon + a "Click here to open/close the app menu!" will signify how to open the app.
• An arrow pointing to the more options icon(s) + a "Click here to see more..." will help the user figure out that the more option chevrons can be opened.
• An arrow pointing to the settings icon + a "a click here for app settings!" will direct the user to Settings.

That's it.

[waydabber]

Untitled.mov

Upon first launch the app menu will open up and some yellow signs will guide the user how to open/close hte menu, expand more options and reach settings. Whenever the uses does any of these, the relevant onboarding sign will just wanish and never comes back.
This should be super simple, intuitive and wowen into app usage.