Add a module extension for registering local/remote jdks

[hvadehra]

No description provided.

[fmeum]

Module extensions typically don't work well if they accept user-provided names while also collecting tags from transitive deps. There just is no good way to handle collisions.

Since this extension would only wrap simple repos, could use_repo_rule be an alternative? If not because the repo rules really are macros, what's blocking them from being rules?

[hvadehra]

Thanks for the heads up. This is just me experimenting for bazelbuild/bazel#26589

If we do go ahead with this, I was imagining only permitting root modules to use this. WDYT?

[fmeum]

Only allowing the root module to use the extension is the best way to resolve this issue.

For local_java_repository specifically, we could also just get rid of the macro wrapper. Then it could be used with use_repo_rule as the reporter of that issue attempted to do.

remote_java_repository necessarily creates two repos and the one with the specified name is not the one users usually need to reference, which makes it pretty incompatible with use_repo_rule even if we add support for macros.