Move add / import button to the top right in the navigation bar

[GianniCarlo]

Purpose

• Users with large libraries have complained that to import new books, they have to scroll to the end, this PR removes that add button at the bottom, and puts it in the navigation bar

Things to be aware of / Things to focus on

This also includes:

• An update for the remote commands to set them in a background thread, as it could add some delay when launching the app
• Sentry SDK update

Screenshots