Provide a way of packaging separate layers into Java container after deprecation of rules_docker

(It feels awkward to ask this question here, but it is a follow-up of [ this suggestion over at rules_oci ](https://github.com/bazel-contrib/rules_oci/issues/416#issuecomment-1832829593))

As the maintainers have decided that the rules_oci repository should remain language agnostic, it is quite unclear where to go with questions for language-specific containers, so following @alexeagle 's advice I am trying over here.

I would like to migrate from rules_docker to rules_oci, but the functionality to package depsets into separate layers has not been provided by the new rules ([_jar_app_layer_impl](https://github.com/bazelbuild/rules_docker/blob/8e70c6bcb584a15a8fd061ea489b933c0ff344ca/java/image.bzl#L178-L212) ).

Would it be possible to provide similar functionality in a `.defs` file in this repository, and could someone help me out in porting it?

首先阅读 rules_docker 的 java/image.bzl 中被引用的 _jar_app_layer_impl，以及链接的 rules_oci 讨论。确定本仓库中等效 depset-to-layer 打包的预期归属位置和范围。完成的标准是：通过 .defs 文件提供所请求的 Java 容器分层功能，并具有从 rules_docker 迁移的清晰路径。

由索引模型根据 Issue 内容生成。