refactor: promote directory_file_path to public API

Users with custom rules need to access this when the rule wants to reference labels within a tree artifact
such as when using exports_directories_only.

Note, I didn't leave anything behind in the private/ folder since the rule implementation is just one line.

This also adds the rule to the documentation, previously only the DirectoryFilePathInfo was documented.

docs/Core.md

diff --git a/docs/Core.md b/docs/Core.md
index 3dd1899..f89aea2 100644
--- a/docs/Core.md
+++ b/docs/Core.md
@@ -21,6 +21,37 @@
 We plan to clean these up and port into `rules_nodejs` in a future major release.
 
 
+## directory_file_path
+
+**USAGE**
+
+<pre>
+directory_file_path(<a href="#directory_file_path-name">name</a>, <a href="#directory_file_path-directory">directory</a>, <a href="#directory_file_path-path">path</a>)
+</pre>
+
+Provide DirectoryFilePathInfo to reference some file within a directory.
+
+        Otherwise there is no way to give a Bazel label for it.
+
+**ATTRIBUTES**
+
+
+<h4 id="directory_file_path-name">name</h4>
+
+(*<a href="https://bazel.build/docs/build-ref.html#name">Name</a>, mandatory*): A unique name for this target.
+
+
+<h4 id="directory_file_path-directory">directory</h4>
+
+(*<a href="https://bazel.build/docs/build-ref.html#labels">Label</a>, mandatory*): a directory
+
+
+<h4 id="directory_file_path-path">path</h4>
+
+(*String, mandatory*): a path within that directory
+
+
+
 ## node_repositories
 
 **USAGE**

internal/common/maybe_directory_file_path.bzl

diff --git a/internal/common/maybe_directory_file_path.bzl b/internal/common/maybe_directory_file_path.bzl
index 41b15f4..dd76d25 100644
--- a/internal/common/maybe_directory_file_path.bzl
+++ b/internal/common/maybe_directory_file_path.bzl
@@ -15,7 +15,7 @@
 """Helper function to accept either a label or a directory_file_path as dict
 """
 
-load("@rules_nodejs//nodejs/private:directory_file_path.bzl", "directory_file_path")
+load("@rules_nodejs//nodejs:directory_file_path.bzl", "directory_file_path")
 
 def maybe_directory_file_path(name, value):
     """Pass-through a value or convert a dict with a single key/value pair to a directory_file_path and return its label

internal/node/test/dir_entry_point/BUILD.bazel

diff --git a/internal/node/test/dir_entry_point/BUILD.bazel b/internal/node/test/dir_entry_point/BUILD.bazel
index aff8ed9..d1e19bf 100644
--- a/internal/node/test/dir_entry_point/BUILD.bazel
+++ b/internal/node/test/dir_entry_point/BUILD.bazel
@@ -1,5 +1,5 @@
 load("@bazel_skylib//rules:write_file.bzl", "write_file")
-load("@rules_nodejs//nodejs/private:directory_file_path.bzl", "directory_file_path")
+load("@rules_nodejs//nodejs:directory_file_path.bzl", "directory_file_path")
 load("@build_bazel_rules_nodejs//:index.bzl", "nodejs_binary", "pkg_npm")
 load("@npm//typescript:index.bzl", "tsc")
 load("//internal/common:assert.bzl", "assert_program_produces_stdout")

nodejs/directory_file_path.bzl

diff --git a/nodejs/private/directory_file_path.bzl b/nodejs/directory_file_path.bzl
similarity index 100%
rename from nodejs/private/directory_file_path.bzl
rename to nodejs/directory_file_path.bzl

nodejs/index.for_docs.bzl

diff --git a/nodejs/index.for_docs.bzl b/nodejs/index.for_docs.bzl
index 268c92e..4275c0d 100644
--- a/nodejs/index.for_docs.bzl
+++ b/nodejs/index.for_docs.bzl
@@ -25,12 +25,14 @@
     _declaration_info = "declaration_info",
     _js_module_info = "js_module_info",
 )
+load(":directory_file_path.bzl", _directory_file_path = "directory_file_path")
 load(":repositories.bzl", _node_repositories = "node_repositories")
 load(":yarn_repositories.bzl", _yarn_repositories = "yarn_repositories")
 load(":toolchain.bzl", _node_toolchain = "node_toolchain")
 
 DeclarationInfo = _DeclarationInfo
 declaration_info = _declaration_info
+directory_file_path = _directory_file_path
 JSModuleInfo = _JSModuleInfo
 js_module_info = _js_module_info
 LinkablePackageInfo = _LinkablePackageInfo