message: Make IsOkAndHolds() use the content type alias compatible with absl::StatusOr.
  Part of the Tink migration towards using absl::Status{,Or}.
diff: @@ -39,7 +39,8 @@ template <typename StatusOrType>
  class IsOkAndHoldsMatcherImpl
  : public ::testing::MatcherInterface<StatusOrType> {
  public:
  - using value_type = typename std::remove_reference<StatusOrType>::type::type;
  + using value_type =
  + typename std::remove_reference<StatusOrType>::type::value_type;
  template <typename InnerMatcher>
  explicit IsOkAndHoldsMatcherImpl(InnerMatcher&& inner_matcher)
  