draft: Appstream related patches

[ghost]

appdata: use appstreamcli for appdata validation

appstream-util is obsoleted by appstreamcli.

appdata: Update appdata

• Add cvs-browser URL.
• Mark the developer name as untranslatable.
• Add Categories and keywords
• Try to fix appdata screenshot error.

[ghost]

There is an error about xml:lang validation.

https://github.com/ximion/appstream/issues/549

[ghost]

Michael Catanzaro recommended the use of appstreamcli in this comment.

[ghost]

Already merged