convert reduce-args to a simplifier

- convert reduce-args to a simplifier. Currently exposed as reduce-args2 tactic until the old tactic code gets removed.
- bug fixes in model_reconstruction trail
  - allow multiple defs to be added with same pool of removed formulas
  - fix tracking of function symbols instead of expressions to filter replay
- add nla_divisions to track (cheap) divisibility lemmas.
-

src/ast/simplifiers/CMakeLists.txt

@@ -19,6 +19,7 @@ z3_add_component(simplifiers
     max_bv_sharing.cpp
     model_reconstruction_trail.cpp
     propagate_values.cpp
+    reduce_args_simplifier.cpp
     solve_context_eqs.cpp
     solve_eqs.cpp
   COMPONENT_DEPENDENCIES