The non-www https URL appears to redirect through a non-https URL before
reaching the www https URL, which triggers a warning in some appstream
validation tools. Instead, just go to the www https URL directly so
there are no redirects needed.
* Switch to using org.kicad.kicad as the main app ID
* Move the appstream file to a metainfo file
* Rename all metadata files to use the reverse DNS scheme
* Add header matching to mime type files where possible
* Add a mime type for gerber job files
* Add a QA test that verifies all the linux metadata files and
run it in CI
* Update the visible names in the launcher entries to be more
consistent with the internal visible names
* Update various strings and items in the metainfo file so they
are more descriptive and easier to read
Ian McInerney