Hide key template instances behind factory functions.

And provide a separate "module library"
Update testing scripts.

module/regex_smatch.cpp

@@ -0,0 +1,26 @@
+
+#if defined(__cpp_lib_modules) || (defined(_MSC_FULL_VER) && (_MSC_FULL_VER >= 193933523))
+#define BOOST_REGEX_USE_STD_MODULE
+#endif
+
+#ifndef BOOST_REGEX_USE_STD_MODULE
+module;
+
+#include <string>
+
+#endif
+
+module boost.regex;
+
+#ifdef BOOST_REGEX_USE_STD_MODULE
+import std;
+#endif
+
+namespace boost::re_detail_600 {
+
+   bool factory_match(perl_matcher<std::string::const_iterator, match_results<std::string::const_iterator>::allocator_type, regex::traits_type>& m)
+   {
+      return m.match();
+   }
+
+}