As per described in @Katoriehooves proposal https://github.com/Ellypse/LibMSP/issues/20, we should expose the profile music theme of the player via LibMSP in the MU field.

Given the user selected a music theme for their profile
When the profile is sent via LibMSP
Then Total RP 3 should provide a new MU field with the path of the music without the Sound\Music\ part of the path.

Technical notes: Total RP 3 might move to using file IDs to pick musics in the future. We would then need to use the GetFileIDFromPath API function to make sure we send a file path to LibMSP, or coordinate with other developers to also support file IDs.