Spring Extend HTTP status assertions

This is an extension for HTTP status assertions in the AbstractHttpServletResponseAssert, which was introduced in version 6.2. With this extension, it is possible to write test assertions like this

MvcTestResult result = mockMvcTester.get().uri("/example").exchange();
assertThat(result).httpStatus().isUnauthorized();

which is inspired by the "old" MockMvc status assertions:

mockMvc.perform(get("/example"))
    .andExpect(status().isUnauthorized());

No breaking changes introduced.