gitlab CI: build an rpm package to verify the installed file list

gitlab CI: build an rpm package to verify the installed file list

This is not a package intended for, it's a job to fail when we accidentally
change the file list. An rpmbuild job like this was what detected
f15da0f10890467712222410233c0bec9faefdd0.

The spec file resembles the Fedora one but has BuildRequires removed (we rely
on the container for that).

The same task could be achieved by keeping a file list and comparing the
installed tree but since I had the rpm spec file already, let's use that for
now.

This requires meson 0.55 which hit F32 yesterday.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>