(proof-new) Update Theory interface for proof-new (#4648)

(proof-new) Update Theory interface for proof-new (#4648)

This includes 4 changes:

Theory constructor takes a ProofNodeManager,
Theory::explain returns a TrustNode (of kind PROP_EXP),
Theory::expandDefinitions returns a TrustNode (of kind REWRITE),
Theory::ppRewrite returns a TrustNode (of kind REWRITE).
These are all currently planned updates to the interface of Theory.
This PR also connects some of the existing proof rule checkers into the proof checker, if one is provided to the constructor. It updates TheoryEngine and other places to process TrustNode in trivial ways (converting them into Node). These calls will later be updated as needed for proof support.

This PR is also contingent on the performance tests for proof-new on SMT-LIB.