feat: 테스트에서 로그인 유저 정보 조회 기능 추가

src/test/kotlin/roomescape/util/RestAssuredUtils.kt

@@ -49,6 +49,11 @@ class LoginUtil(
     fun loginAsUser(): String {
         return login(MemberFixture.user.email, MemberFixture.user.password)
     }
+
+    fun getUser(): MemberEntity = memberRepository.findByEmailAndPassword(
+        MemberFixture.user.email,
+        MemberFixture.user.password
+    ) ?: throw AssertionError("Unexpected Exception Occurred.")
 }
 
 fun runTest(