predefined-instruments: add ATB custom Voice contexts
predefined-instruments: remove \addlyrics to have proper voice contexts

With \addlyrics, the notes weren't placed in a SopranoVoice,
just in an ordinary Voice (despite using \defaultchild).

This was because \addlyrics says "hey, I need a Voice" right
after SopranoStaff has been created, and gets the demanded Voice.
And then a Bottom context is there, so SopranoVoice isn't created.

Without \addlyrics, we get the expected result.
predefined-instruments: add \dynamicUp and \tupletUp
predefined-instruments: move Staff_performer

We move this performer from Staff contexts to Voice contexts
so that there separate MIDI channels will be created for each
voice (even if there are multiple voices on one Staff).