Expand node version file support to include lts based codenames

src/node-version.ts

@@ -0,0 +1,21 @@
+import * as hc from '@actions/http-client';
+
+//
+// Node versions interface
+// see https://nodejs.org/dist/index.json
+//
+export interface INodeVersion {
+  version: string;
+  files: string[];
+  lts: boolean | string;
+}
+
+export async function getVersionsFromDist(): Promise<INodeVersion[]> {
+  let dataUrl = 'https://nodejs.org/dist/index.json';
+  let httpClient = new hc.HttpClient('setup-node', [], {
+    allowRetries: true,
+    maxRetries: 3
+  });
+  let response = await httpClient.getJson<INodeVersion[]>(dataUrl);
+  return response.result || [];
+}