World/deja-dup 49.0 on GNOME GitLab

Enable Restic by default in all builds
Redesign the UI to be a bit more modern
Fix stale "last backed up" timestamps when open for more than a day
Tweak when automatic backups are scheduled to be less surprising
(base them directly off the last backup, not off predetermined windows)
Use nice & ionice on subprocesses in more cases
Rclone: when running under flatpak, look for config in ~/.config/rclone/
Rclone: confirm remotes are actually valid before trying to use them
Restic: use the file manager instead of our custom browser when
restoring
Restic: surface some errors that were slipping through the cracks
Duplicity: support ~/.cache/deja-dup being a symlink
Duplicity: fix possibility of accidentally changing password for new full
backups, with newer versions of duplicity

There are several updates to make, as Restic is now the default tool backend.
Below is a summary. More details can be found on the wiki,
including advice on the version of Restic to use:
https://gitlab.gnome.org/World/deja-dup/-/wikis/Packaging-Changes

The enable_restic and restic_by_default meson options are now ignored
and Restic support is now required. You should add a runtime dependency on
Restic and optionally set the related options restic_pkgs (if using
PackageKit) and restic_command (if Restic isn't installed in PATH).
You should keep a runtime dependency on Duplicity. Existing Duplicity backups
are still supported and are not converted to Restic. If depending on two
backup programs feels bloated or is difficult, turn on PackageKit support
and let Deja Dup install Duplicity on-demand.
You should add a runtime dependency on fusermount (or fusermount3) - likely
provided by a fuse2 or fuse3 package. Use the new fusermount_command
meson option if it is installed outside of PATH.
Require blueprint-compiler 0.14+
Require libadwaita 1.8+
Require meson 1.1+
Drop the libgpg-error dependency

Rclone: when running under flatpak, look for config in ~/.config/rclone/
Restic: fix bashism in fusermount script that mounts restore files
Restic: surface some errors that were slipping through the cracks
Duplicity: fix possibility of accidentally changing password for new full
backups, with newer versions of duplicity