Add `value` attribute alias to `@MockitoBean` and `@MockitoSpyBean`

[sbrannen]

@TestBean currently supports name and value aliases; however, @MockitoBean and @MockitoSpyBean only support a name attribute which requires users to type @MockitoBean(name = "userService") instead of simply @MockitoBean("userService").

To improve the user experience for common cases, we should introduce new value attributes in @MockitoBean and @MockitoSpyBean as aliases for the existing name attributes.