This commit upgrades the default CNB builder image from
cloudfoundry/cnb:0.0.43-bionic to cloudfoundry/cnb:0.0.53-bionic.
It also adds integration tests for the Maven and Gradle plugins
to verify both versions are supported.
With the introduction of Gradle we lost the list of version properties
that were previously in the spring-boot-dependencies POM and were also
linked inside the documentation. This commit introduces an appendix
section in the docs and links the appropriate places to the new section
to restore discoverability.
See gh-19898
Update all dependencies declarations to use the form `scope(reference)`
rather than `scope reference`.
Prior to this commit we declared dependencies without parentheses unless
we were forced to add them due to an `exclude`.
