Add problem matcher for `appstream-util validate`'s output

[rffontenelle]

See https://github.com/vixalien/sticky/issues/59#issuecomment-1554644759

I'm still trying to figure out how to also annotate the filename, hence made this a draft.

[ghost]

I think appstreamcli works better than appstream_util and easily catches these errors.

[vixalien]

Indeed. I believe this is fixed by #110