[sat] Add option to disable Minisat simplifications (#7992)

[sat] Add option to disable Minisat simplifications (#7992)

Useful to better control behavior, specially in terms of how the solver performs
when these simplifications (mainly variable and clause elimination) are
disabled, e.g. with incremental and/or proofs.

Also renames the previously confusing "--minisat--elimination" option, which
only refers to variable elimination, a subset of the Minisat simplifications.

Moreover deletes an old comment which no longer applies.