adding simplifiers layer

simplifiers layer is a common substrate for global non-incremental and incremental processing.
The first two layers are new, but others are to be ported form tactics.

- bv::slice - rewrites equations to cut-dice-slice bit-vector extractions until they align. It creates opportunities for rewriting portions of bit-vectors to common sub-expressions, including values.
- euf::completion - generalizes the KB simplifcation from asserted formulas to use the E-graph to establish a global and order-independent canonization.

The interface dependent_expr_simplifier is amenable to forming tactics. Plugins for asserted-formulas is also possible but not yet realized.

src/tactic/bv/CMakeLists.txt

@@ -8,6 +8,7 @@ z3_add_component(bv_tactics
     bv_bound_chk_tactic.cpp
     bv_bounds_tactic.cpp
     bv_size_reduction_tactic.cpp
+    bv_slice_tactic.cpp
     dt2bv_tactic.cpp
     elim_small_bv_tactic.cpp
     max_bv_sharing_tactic.cpp
@@ -21,6 +22,7 @@ z3_add_component(bv_tactics
     bv_bound_chk_tactic.h
     bv_bounds_tactic.h
     bv_size_reduction_tactic.h
+    bv_slice_tactic.h
     bvarray2uf_tactic.h
     dt2bv_tactic.h
     elim_small_bv_tactic.h

src/tactic/bv/bv_slice_tactic.h

@@ -0,0 +1,29 @@
+/*++
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    bv_slice_tactic.h
+
+Abstract:
+
+    Tactic for simplifying with bit-vector slices
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2022-10-30
+
+--*/
+#pragma once
+
+#include "util/params.h"
+class ast_manager;
+class tactic;
+
+tactic * mk_bv_slice_tactic(ast_manager & m, params_ref const & p = params_ref());
+
+/*
+  ADD_TACTIC("bv-slice", "simplify using bit-vector slices.", "mk_bv_slice_tactic(m, p)")
+*/
+
+