All it wants is to use the main trigger state, so don't bother copying it. Instead, change
PwmConfig to take a const pointer to a Multi.*Sequence, then make all the users adapt. Worse
fallout is that SimplePwm now has its own Multi.*Sequence, but PwmConfig is downgraded to a
pointer, so that's only a net +4 bytes. And we can make the overhead of Multi.*Sequence much lower
using embedded arrays, which only the caller can do since it knows the maximum size... (for another
day...)
Also remove SimplePwm's 2nd copy of SingleChannelStateSequence. It served no purpose.
Saves 1992 bytes of BSS and 24 bytes of RAM4 (latter probably due to SimplePwm change)