Move language-selector-common to the desktop-common seed
The history indicates this is useful for the server installer, but:
- the server installer makes no use of it
- if it did, it could be seeded in the installer squashfs instead of in the
rootfs where it would be unused post-install
- nearly everything this package will install is specific to desktop
(fonts, input methods, ...)
- seeding it in standard also pulls it into cloud images, which is where
I noticed this as a result of LP: #1871538
I think this should be pushed up to desktop-common given its actual usage.
Was previously pulled in as a dependency of mime-support, and this is a
widely-used compression format that we should keep installed by default
along with gzip. bzip2 has also dropped out of the seed, but not seeding
this directly as that is a compression format that is largely superseded
by xz in practice.