(new theory) Update TheoryArrays to the new standard (#5000)

(new theory) Update TheoryArrays to the new standard (#5000)

This includes using the standard d_conflict flag in TheoryState and splitting its check into 3 callbacks.

It also deletes some unused code and eliminates an assertion (line 791 of theory_arrays.cpp) which doesn't hold in a central architecture.

Further work on standardization for arrays will add an InferenceManager to guard its uses of asserting facts to equality engine (both for proofs and configurable theory combination).

FYI @barrettcw