Remove the `spring-boot-web-server-test` module, adding
`SpringBootTestRandomPortContextCustomizerFactory` to
`spring-boot-web-server` as a replacement for
`SpringBootTestRandomPortApplicationListener`.
See gh-46356
See gh-47322
Relocate `RestTestClientBuilderCustomizer` to `spring-boot-test`
and break the direct link to web-server by making use of
`spring.factories` and the new `BaseUrlProviders` class.
See gh-46356
Phillip Webb
Stéphane Nicoll