Update theory of arithmetic to standard check (#5178)

Update theory of arithmetic to standard check (#5178)

This updates the theory of arithmetic to use the standard check callbacks (preCheck, postCheck, preNotifyFact, notifyFact). It also refactors some use of the non-linear solver which will solely live in TheoryArith.

The longer term goal is to have TheoryArithPrivate be responsible for linear arithmetic solving only, and to be treated as a black box. Eventually, the non-linear solver will be removed from this class.

This PR is required for several things, including refactoring of preprocessing and expand definitions for arithmetic (div/mod will not be eliminated eagerly). It is also required for fixing issues related to div/mod appearing in instantiations.

This is the last class to have a custom check method. Followup PR will make Theory::check non-virtual.