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
transitive = false maps to a wildcard exclusion in the published pom.
Unfortunately, this causes problems with Maven as any dependency
on one of the transitive = false modules then has all of its
dependencies excluded, even when it appears elsewhere in the
dependency graph without any exclusions.
Gradle is not affected as it requires an exclusion to be declared
on every route to a dependency for it to be effective. Maven is
affected as it requires the exclusion to be present on only one
route.
Phillip Webb
Moritz Halbritter
Andy Wilkinson