RPM friendly path structure in config

[xsuchy]

As I am experimenting with appstream-generator, I found the path structure inconvinient.

appstream-generator concat section and architecture. Which enforces the path section/architecture/os - and I found no way to customize this. In rpm world, we use just $section-$version-$arch. E.g. fedora-36-x86_64, fedora-rawhide-s390x.

I tried to workaround it by specifying . as architecture which resulted in fedora/./ which is a valid pathname for path fedora/ but appstream-generator fails to use such a path.

[ximion]

Maybe we can make this configurable, or dependent on the use of the rpmmd backend... (but I wouldn't mind an extra configuration option for this at all, seems to be quite straightforward and easy to maintain).

[Conan-Kudo]

It would probably make sense to make this fully configurable, because the Open Build Service generates "simple" debian repositories too, which would also benefit from being able to have their appstream data generated too.