AssertJ support for RestTestClient #35701
Description
MockMvcTester added AssertJ support response assertions, and while it's integrated with MockMvc, it could also be integrated in other places like RestTestClient.
We have a request #35624 for JsonContentAssert, but we can aim more broadly to replicate the MockMvcTester experience for RestTestClient by wrapping an ExchangeResult rather than an MvcResult.