Allow to configure "start view" in the files app

[susnux]

Just had a call with @kra-mo:
Short version: In this specific case, the best solution seems to be indeed to have a setting. It should be a radio control with 3 options. Group name "Start in" and options are:

• Home (default)
• All files
• Personal files

We came to this conclusion after discussing the following points:

• On first run after the update, people will start in the home view. If they don’t like it, they can disable it. But this is common practice on other platforms.
• Adding the feature but still only starting in "All files" would be strange and make the home view essentially useless and undiscoverable.
• Remembering the last navigation entry (like in Mail) is unfortunately not possible in Files because elements in "Home" and in many other views as well just redirect to "All files".
• A tabbed view for home, if we would like it, is a bigger topic and thus a discussion for another cycle.

Originally posted by @jancborchardt in #49474