add bv-size reduce #6137

- add option smt.bv.reduce_size.
  - it allows to apply incremental pre-processing of bit-vectors by identifying ranges that are known to be constant.
    This rewrite is beneficial, for instance, when bit-vectors are constrained to have many high-level bits set to 0.

src/smt/params/theory_bv_params.h

@@ -36,6 +36,7 @@ struct theory_bv_params {
     bool         m_bv_enable_int2bv2int = true;
     bool         m_bv_watch_diseq = false;
     bool         m_bv_delay = true;
+    bool         m_bv_size_reduce = false;
     theory_bv_params(params_ref const & p = params_ref()) {
         updt_params(p);
     }