Use GtkHeaderBar and CSD

This involves removing the ability to select multiple devices, hence
the ability to create RAID arrays. The RAID functionality will be
completely removed in a follow-up commit.

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
Remove MD-RAID support

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
Use flat list in device tree

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
Use media icon, if available

Now that we only show a single icon, it makes sense to choose the
media icon if there is one.

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
libgdu: Fix deprecation warnings

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
disk-image-mounter: Fix deprecation and other warnings

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
notify: Fix deprecation and other warnings

Signed-off-by: David Zeuthen <zeuthen@gmail.com>
disks: Fix deprecation and other warnings

Signed-off-by: David Zeuthen <zeuthen@gmail.com>