x2t: implement set/getMetadata
Cloudooo takes the first handler that can "handle" source_mimetype.
However, docx can be "handled" by ooo and x2t, but documents metadata can only be "handled" by the ooo handler.
Cloudooo takes the first handler that can "handle" source_mimetype.
However, docx can be "handled" by ooo and x2t, but documents metadata can only be "handled" by the ooo handler.