Add simplification customization for SMTLIB2

Add the ability to customize incremental pre-processing simplification for the SMTLIB2 front-end. The main new capability is to use pre-processing tactics in incremental mode that were previously not available. The main new capabilities are
- solve-eqs
- reduce-args
- elim-unconstrained
There are several more. Documentation and exposed simplifiers are populated incrementally. The current set of supported simplifiers can be inspected by using z3 with the --simplifiers flag or referring to https://microsoft.github.io/z3guide/docs/strategies/simplifiers

Some pending features are:
- add the ability to update parameters to simplifiers similar to how tactics can be controlled using parameters.
- expose simplification solvers over the binary API.

src/cmd_context/CMakeLists.txt

@@ -9,6 +9,7 @@ z3_add_component(cmd_context
     parametric_cmd.cpp
     pdecl.cpp
     simplify_cmd.cpp
+    simplifier_cmds.cpp
     tactic_cmds.cpp
     tactic_manager.cpp
   COMPONENT_DEPENDENCIES