feat(docs-infra): add the ability to expose globals (#34237)

Adds the ability to expose global symbols in the API docs via the `@globalApi` tag. Also supports optionally setting a namespace which will be added to the name automatically (e.g. `foo` will be renamed to `ng.foo`). Relevant APIs should also be exported through the `global.ts` file which will show up under `core/global`.

PR Close #34237

aio/tools/transforms/angular-api-package/processors/addGlobalApiData.js

@@ -0,0 +1,28 @@
+/**
+ * @dgProcessor addGlobalApiData
+ *
+ * Marks APIs tagged with `@globalApi` as globals and
+ * prefixes them with the namespace, if there is one.
+ */
+module.exports = function addGlobalApiDataProcessor() {
+  return {
+    $runBefore: ['computing-ids'],
+    $process: function(docs) {
+      docs.forEach(doc => {
+        const globalApiTag = doc.globalApi && doc.globalApi.trim();
+
+        if (globalApiTag != null) {
+          doc.global = true;
+
+          if (globalApiTag.length > 0) {
+            // Prefix the symbol name with the global namespace,
+            // if we have one (e.g. `foo` becomes `ng.foo`).
+            doc.unprefixedName = doc.name;
+            doc.name = `${globalApiTag}.${doc.name}`;
+            doc.globalNamespace = globalApiTag;
+          }
+        }
+      });
+    }
+  };
+};