Retrieve all app navigations to prevent reloading appinfo/app.php and
causing an error when the app isn't fully loaded. The addition/deletion
logic has been moved to JS, simplifying a lot of code.
This enforces proper types on POST and GET arguments where I considered it sensible. I didn't update some as I don't know what kind of values they would support 🙈
Fixes https://github.com/owncloud/core/issues/14196 for core
Morris Jobke
Robin McCorkell
Jenkins for ownCloud
Lukas Reschke
Thomas Müller
Bart Visscher