Reimplement, reorganize, and fix a number of solo handling things

[TheNathannator]

Summary:

• Solo phrases now have their note counts pre-calculated, and are now excluded if they contain no notes (overdrive phrases are also now excluded if they have no notes).
• All text creation related to the solo box has been moved to TrackView, rather than the methods there accepting strings they take the actual values and turn those into strings themselves.
• The solo score bonus has been re-added, along with displaying it after a solo.
• The solo textbox is now colored again using the vertex colors that were present in the previous implementation. This time they've been turned into asset files, and can now be used on any other textbox if desired.
• The previously commented-out code has been removed now that it's fully reimplemented.
• Solos now wait for their first note to be the current note before starting.
• A special result has been added for anyone who breaks solos again lol