Moved matcher-based capture macros into their own file

- this file excluded from the CATCH_CONFIG_DISABLE_MATCHERS path.
- matchers are always compiled in to the impl file
- _THROWS_WITH macros are still available with matchers disabled - but only the ones that take a string
- tests that use matchers have #ifdefs, so the whole SelfTest project can compile with matchers disable.

projects/SelfTest/MatchersTests.cpp

@@ -8,6 +8,8 @@
 
 #include "catch.hpp"
 
+#ifndef CATCH_CONFIG_DISABLE_MATCHERS
+
 inline const char* testStringForMatching()
 {
     return "this string contains 'abc' as a substring";
@@ -223,3 +225,5 @@ TEST_CASE("Exception matchers that fail", "[matchers][exceptions][!throws][.fail
         REQUIRE_THROWS_MATCHES(throws(4), SpecialException, ExceptionMatcher{ 1 });
     }
 }
+
+#endif // CATCH_CONFIG_DISABLE_MATCHERS