Rename org.kde.minuet.appdata.xml to org.kde.minuet.metainfo.xml

https://freedesktop.org/software/appstream/docs/chap-Metadata.html#spec-component-location
says "Note Component metadata of type desktop-application as described in
Section 2.3, “Desktop Applications” can be installed with an .appdata.xml
extension as well for historical reasons. AppStream implementations will
read the XML files as long as they end up in the right location on the
filesystem.".