Add asymmetric equality tester to match a string against a regexp

- Also move the asymmetric testers into their own dir for easier
  locating.

[#58120558] Fix #243

src/core/requireCore.js

@@ -36,6 +36,7 @@ getJasmineRequireObj = (function (jasmineGlobal) {
     j$.Spec = jRequire.Spec(j$);
     j$.SpyRegistry = jRequire.SpyRegistry(j$);
     j$.SpyStrategy = jRequire.SpyStrategy();
+    j$.StringMatching = jRequire.StringMatching(j$);
     j$.Suite = jRequire.Suite();
     j$.Timer = jRequire.Timer();
     j$.version = jRequire.version();