build(aio): refactor dgeni packages

This is to tidy up the `author-packagse`, which currently duplicates a
lot of the configuration in the main packages. We need to
DRY this up so that we don't fall foul of a change in one being missed in
the other.

aio/tools/transforms/angular-base-package/rendering/toId.js

@@ -0,0 +1,6 @@
+module.exports = function toId() {
+  return {
+    name: 'toId',
+    process: function(str) { return str.replace(/[^(a-z)(A-Z)(0-9)._-]/g, '-'); }
+  };
+};