Keep File View's Search Field and Source List's states persistent between uses

Currently (in Blender 3.0 and older), when one opens a File View several times in a session (for, say, importing a series of objects), the File View remembers some of its previous state:

• Last browsed directory (although not in all circumstances).
• Last processed File's Name.
• Last Display Mode.

I propose that it remembers too the following:

• Search field's last used filter.
• Order of the Source List Region's elements (Volumes, System, Bookmarks, etc.) and their states (expanded/collapsed).

The former would be most useful when dealing with directories holding hundreds of files, given that many importers force us to import them one by one.