Googletest export

Change Matcher<T> to allow binding an implementation by value directly:
 - Drop the requirement of MatcherInterface. Doing manual type erasure avoid
   extra layers in many cases.
 - Avoid the adaptor for `MatcherInterface<T>` and `MatcherInterface<const T&>` mismatch.
 - Use a small object optimization when possible. This makes things like
   `_` and `Eq(1)` really cheap and do not require memory allocations.
 - Migrate some matchers to the new model to speed them up and to test the new framework. More matchers to come in future changes.

PiperOrigin-RevId: 350580998

googlemock/test/gmock-matchers_test.cc

@@ -410,7 +410,7 @@ TEST(StringMatcherTest,
 // MatcherInterface* without requiring the user to explicitly
 // write the type.
 TEST(MakeMatcherTest, ConstructsMatcherFromMatcherInterface) {
-  const MatcherInterface<int>* dummy_impl = nullptr;
+  const MatcherInterface<int>* dummy_impl = new EvenMatcherImpl;
   Matcher<int> m = MakeMatcher(dummy_impl);
 }