mpdmenu: Use MBIDs for track matching instead of name matching.

mpdmenu: Use MBIDs for track matching instead of name matching.

Instead of guessing based on titles, match tracks by their work MBID.

This makes the title menu significantly simpler as we remove all the
title-specific special cases.  This approach gives results pretty close
to what we got originally (much better in some cases), but currently
things like different symphony movements which used to show up in the
menu are not handled.