Relocate `WebTestClientBuilderCustomizer` to `spring-boot-test`
and break the direct link to web-server and http-codec by making
use of `spring.factories` and the new `BaseUrlProviders` class.
A new `spring-boot-test-integration-test` module has also been
added to ensure hold the previous tests.
See gh-46356
Drop `isImmutable` and `getPrefix` from `OriginLookup` since
they're not really Origin concerns. Now that `env` is a
foundational layer we can add a dedicated `PropertySourceInfo`
interface and add that to the `o.s.b.env` package without
creating a package tangle.
Closes gh-45547
Move the `EnvironmentPostProcessor` from `org.springframework.boot.env`
to `org.springframework.boot` so that we can make the `env` package
foundational.
Most `EnvironmentPostProcessor` implementation has also been relocated
to a new `org.springframework.boot.support` package.
See gh-47232
Move bootstrap code from `org.springframework.boot` to
`org.springframework.boot.bootstrap` and make them a foundational
layer.
This move helps reduce `org.springframework.boot.context.config`
dependencies to `org.springframework.boot`.
See gh-47232
Phillip Webb
Moritz Halbritter