Use QuicheTest and quiche_test.h in third_party/http2. The motivation is that these files have to be included with #pragma clang diagnostic ignored "-Weverything", otherwise CLs touching test files will not build. PiperOrigin-RevId: 334632337 Change-Id: I74d8cdef4b07eed79880d1ca7e0476b3a2c5c184