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/cmd_context.cpp

@@ -546,6 +546,7 @@ cmd_context::cmd_context(bool main_ctx, ast_manager * m, symbol const & l):
     install_basic_cmds(*this);
     install_ext_basic_cmds(*this);
     install_core_tactic_cmds(*this);
+    install_core_simplifier_cmds(*this);
     m_mcs.push_back(nullptr);
     SASSERT(m != 0 || !has_manager());
     if (m_main_ctx) {
@@ -559,8 +560,7 @@ cmd_context::~cmd_context() {
     }
     pop(m_scopes.size());
     finalize_cmds();
-    finalize_tactic_cmds();
-    finalize_probes();
+    finalize_tactic_manager();
     m_proof_cmds = nullptr;
     reset(true);
     m_mcs.reset();