Migrate a majority of the functionality in parsers to the new API (#3838)

Migrate a majority of the functionality in parsers to the new API (#3838)

This PR migrates a majority of the functionality of the parsers (cvc, tptp, smt2/sygus) to the new API. The main omitted functionality not addressed in this PR is the datatypes. Largely, the Expr-level Datatype is still used throughout.

Remaining tasks:

Migrate the Datatypes to the new API in cvc/smt2.
Eliminate the use of ExprManager::mkVar (with flags for DEFINED/GLOBAL).
For the latter, I have made a utility function in Parser::mkVar that captures all calls to this function. Notice that the existing mkVar/mkBoundVar/mkDefinedFun have been renamed to the more fitting names bindVar/bindBoundVar/bindDefinedFun etc.

Note: this PR contains no major code changes, each line of code should roughly correspond one-to-one with the changed version.

This fixes CVC4/cvc4-projects#77, fixes CVC4/cvc4-projects#78, fixes CVC4/cvc4-projects#80, fixes CVC4/cvc4-projects#85.