move closure conversion to solver internalization

- only the internalizer performs closure conversion
- theory_array treats propagation of lambdas similar to stores
- ho_matcher treats top-level flex patterns as first-order
- pattern-inference fix to handle quantifiers (lambdas) in patterns that are computed

src/ast/pattern/pattern_inference.cpp

@@ -384,6 +384,8 @@ bool pattern_inference_cfg::contains_subpattern::operator()(expr * n) {
             break;
         case AST_VAR:
             break;
+        case AST_QUANTIFIER: 
+            break;
         default:
             UNREACHABLE();
         }