This lets Angular Bazel users install our transitive deps, rather than have to list them in their WORKSPACE file.
If they want a different version of one of these deps, they just need to install it before calling rules_angular_dependencies.
PR Close#26488
Angular Package Format v6 stops bundling files in the esm5 and esm2015
directories, now that Webpack 4 can tree-shake per-file.
Adds some missing files like package.json to make packages closer to
what we publish today.
Refactor ng_package to be a type of npm_package and re-use the packaging
action from that rule.
PR Close#22782
Alex Eagle