sim: msp430: move arch-specific settings to internal header

sim: msp430: move arch-specific settings to internal header

There's no need for these settings to be in sim-main.h which is shared
with common/ sim code, so drop the msp430-sim.h include and move it to
the few files that actually need it.

While we're here, drop redundant includes from sim-main.h:
* sim-config.h & sim-types.h included by sim-basics.h already
* sim-engine.h included by sim-base.h already
And move sim-options.h to the one file that needs it.