[lua-factory] fixing resolve-keys and may-resolve

Now we can set the media type to the resolve operation; To the others
keys, we must set true to the mandatory metadata-keys and false to the
others keys that may help in the resolve operation if any.
[lua-factory] Handling config keys from lua or user

In lua, we can set default values for config keys or set it true for
mandatory configs and false to optional configs.
[metrolyrics] update resolve_keys