Add Appstream metainfo

This adds appstream metainfo so that we display correct data
in e.g. GNOME Software, etc. This is useful even if we sideload
the Flatpak as then we display in the list of installed software,
and the version number is listed correctly in 'flatpak list'.

com.blackmagic.Resolve.yaml

@@ -31,11 +31,14 @@ modules:
       - |
         ./download_resolve.sh -p davinci-resolve
         ./setup_resolve.sh
+        ./appdata.sh
         install -Dm755 resolve.sh /app/bin/resolve.sh
     sources:
       - type: file
         path: download_resolve.sh
       - type: file
         path: setup_resolve.sh
+      - type: file
+        path: appdata.sh
       - type: file
         path: resolve.sh