[FR]: re-introduce "managed_directories" workflow

[alexeagle]

What is the current behavior?

Back in rules_nodejs, we had Bazel add a managed_directories feature so that the node_modules tree only has to be installed once, and can be symlinked from Bazel's copy back to the source tree.

Now that it's been removed (https://docs.google.com/document/d/1u9V5RUc7i6Urh8gGfnSurxpWA7JMRtwCi1Pr5BHeE44/edit) users just have to pnpm install in their source tree again, and that can drift out-of-date from the node_modules tree that rules_js manages behind the scenes.

Bazel itself is in the way here, however the Aspect CLI gives us the necessary spot to add such a feature, as it can keep all the wksp/path/to/pkg/node_modules symlinks updated and pointing into the bazel-out tree where we create them.

Describe the feature

Allows users to configure the build so that local tooling like editors "just works" after the first bazel build.

Implementation Notes

Symlinking node_modules into bazel-bin:

• ✅ navigates into bazel-bin for third-party packages (if that package has been built by bazel)
• ✅ navigates into local source for pnpm project references which do not use out/rootDir
• ❌ navigates into bazel-bin for pnpm projects with out/rootDir

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