build: Allow hardcoded-popular plugin to be disabled

Distros might want to completely control the list of popular apps, and
since all the API and metadata is set up to make the list additive
(removing things from it is hard), we need a way to be able to disable
the hardcoded plugin.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
1 job for allow-disabling-hardcoded-popular-plugin in 20 minutes and 9 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #324495
build-gnome-software

00:20:09