d/control: fill in missing fields and improve packages descriptions

This commit fills in the missing URLs in the control file, improves each 
package description a bit so they fully reflect the package contents and 
usage, and adds a number of small fixes:
- wireplumber's section changed from `net` to `video`
- set the utopia team as maintainer

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>