Add a new `spring-boot-layertools` module which provides jarmode support
for working with layers. The module works with both classic fat jars,
as well as layered jars.
Closes gh-19849
Add a Java implementation of the buildpacks.io specification allowing
projects to be packaged into OCI containers. The `builder` class
provides a Java equivalent of `pack build` command and is based on
the `pack` CLI Go code published at https://github.com/buildpacks/pack.
Closes gh-19828