Add `@WebIntegrationTest` which is similar to `@IntegrationTest` and
`@WebAppConfiguration`. The annotation using Spring's `@BootstrapWith`
annotation rather than `@TestExecutionListeners` which allows it to
work when `@TestExecutionListeners` (even ServletTestExecutionListener)
are declared on the test class.

This annotation is particularly useful for TestNG users that extend
Spring's `AbstractTestNGSpringContextTests` class.

Fixes gh-2299
See gh-1956
See gh-2135