Added AbstractOidcProviderConfigTest and AbstractSamlProviderConfigTest and extended them to run the same set of integration tests with both FirebaseAuth and TenantAwareFirebaseAuth.
Added OidcProviderConfigFixture and SamlProviderConfigFixture to further facilitate above parametrized execution style.
As a further cleanup action, moved the concrete fixture classes inside the test classes where they are used:
AbstractOidcProviderConfigTestandAbstractSamlProviderConfigTestand extended them to run the same set of integration tests with bothFirebaseAuthandTenantAwareFirebaseAuth.OidcProviderConfigFixtureandSamlProviderConfigFixtureto further facilitate above parametrized execution style.FirebaseAuthFixture-->FirebaseAuthTest.FixtureTenantAwareFirebaseAuthFixture-->TenantAwareFirebaseAuthTest.Fixture