feat(bazel): add an ng_package rule (#22221)

This produces a directory following the Angular Package layout spec.

Includes integration test coverage by making a minimal ng_package in integration/bazel.
Unit tests verify the content of the @angular/core and @angular/common packages.

This doesn't totally match our current output, but is good enough to unblock some
early adopters.

It re-uses logic from the rollup_bundle rule in rules_nodejs. It should also
eventually have the .pack and .publish secondary targets like npm_package rule.

PR Close #22221

integration/bazel/WORKSPACE

@@ -1,10 +1,14 @@
 workspace(name = "bazel_integration_test")
 
+# Using a pre-release snapshot to pick up a commit that makes all nodejs_binary
+# programs produce source-mapped stack traces and uglify sourcemaps.
+RULES_NODEJS_VERSION = "4303cbef12e5e252ad66cc35cff1123e3a44ee83"
+
 http_archive(
     name = "build_bazel_rules_nodejs",
-    url = "https://github.com/bazelbuild/rules_nodejs/archive/0.4.1.zip",
-    strip_prefix = "rules_nodejs-0.4.1",
-    sha256 = "e9bc013417272b17f302dc169ad597f05561bb277451f010043f4da493417607",
+    url = "https://github.com/bazelbuild/rules_nodejs/archive/%s.zip" % RULES_NODEJS_VERSION,
+    strip_prefix = "rules_nodejs-%s" % RULES_NODEJS_VERSION,
+    sha256 = "fccb9a7122f339d89c9994dc0fea33c737dd76e66281d0da0cb841da5f1edec7",
 )
 
 load("@build_bazel_rules_nodejs//:defs.bzl", "node_repositories")