Remove dead guitar & bass code. Perhaps unify drum & taiko code

[twopointzero]

Can you write a one-sentence description of your request?
We should remove dead guitar and bass code, and consider unifying the remaining drum and taiko code paths.

What is the current behavior?
TJAPlayer3 still operates internally much like its multi-instrument origin, carrying code and executing logic related to instruments that no longer exist.

What is the expected behavior?
There should only be a single instrument code path related to taiko (or drums, but not both.)

What is the motivation / use case for changing the behavior?

• Maintainability first and foremost
  • e.g. Significant dead code and duplicate code
  • e.g. Unnecessary conditionals and iterative code
• Performance as a secondary concern