Collection objects serialize to the same file they're deserialized from

[a-rich]

Is your feature request related to a problem? Please describe.
Since all the Collection features are operating on exported versions of a user's collection, and djtools offers sync functionality to backup these exports, the default behavior of the serialize operations should be to overwrite the path used to deserialize the object. This means users of, say, Rekordbox, can have the software configured to read their COLLECTION_PATH as their rekordbox XML and not have to ever switch it back-and-forth between COLLECTION_PATH and the "auto_" prefixed version of it.

Describe the solution you'd like
Have RekordboxCollection serialize to self._path rather than self._path.parent / f"auto_{self._path.name}".

[a-rich]

This is included in the releases/2.7.0 branch and the latest beta release.