d/control: Use metapackage instead of meta package

See merge request Librem5/librem5-base!6

librem5-gnome: Add virtboard

See merge request Librem5/librem5-base!5

This makes lintian happy

Got lost in the transition to the meta package somehow.

Rename the package to not only handle themes and introduce meta packages

Closes #1

See merge request Librem5/librem5-themes!4

This helps us declutter the image bootstrap and makes it more obvious
why we have what in the image.

Rename the themes package while at that.

Closes: #1

Add polkit rules for MM

Closes phosh#34

See merge request Librem5/librem5-themes!3

We might want to change the package name later on but for the moment
we only ship three files.

Gbp-Dch: Ignore