* Reformat GTK *.ui files
Remove useless comments since we're mostly editing those files by hand
now. Wrap multi-line text values in CDATA to avoid automated formatters
changing whitespace there in any way. Collapse empty elements.
* Switch from plain `GtkLabel`s to `GtkFrame`s for sections
Frames are reported as groupings by assistive technologies.
* Fix minor usability issues
* Make value labels labelled and selectable
* Add compat operator* for RefPtr
* Rename `*_tree_view_*` button handling helpers to `*_item_view_*`
* Move torrent item colors to CSS
* Switch to list view for torrents list (GTK 4)
* Bump Fedora image to 39 (current rawhide) for GTK 4.11
Enable deprecations as there're lots of them in 4.11 and I'm not keen on
fixing them all right now. Disable warnings as errors due to
-Warray-bounds issue somewhere in libfmt.