build: use native ESM and improve templates script performance

This commit refactors the `scripts/templates.mts` file with several improvements:
- Uses a native ESM import for `@angular/ng-dev`.
- Replaces all synchronous `fs` calls with their `fs.promises` counterparts.
- Optimizes file reading by using `Promise.all` to read files concurrently.

Author: clydin

scripts/templates.mts

@@ -7,40 +7,42 @@
  */
 
 import lodash from 'lodash';
-import * as fs from 'node:fs';
+import { readFile, writeFile } from 'node:fs/promises';
 import * as path from 'node:path';
 import { releasePackages } from './packages.mjs';
 
 const __dirname = import.meta.dirname;
 
-async function _runTemplate(inputPath: string, outputPath: string) {
+async function runTemplate(inputPath: string, outputPath: string) {
   inputPath = path.resolve(__dirname, inputPath);
   outputPath = path.resolve(__dirname, outputPath);
 
   console.info(`Building ${path.relative(path.dirname(__dirname), outputPath)}...`);
 
-  // TODO(ESM): Consider making this an actual import statement.
-  const { COMMIT_TYPES, ScopeRequirement } = await new Function(
-    `return import('@angular/ng-dev');`,
-  )();
+  const { COMMIT_TYPES, ScopeRequirement } = await import('@angular/ng-dev');
 
-  const monorepo = JSON.parse(fs.readFileSync('./.monorepo.json', 'utf-8'));
-  const content = lodash.template(fs.readFileSync(inputPath, 'utf-8'))({
+  const [monorepoRaw, templateContent] = await Promise.all([
+    readFile('./.monorepo.json', 'utf-8'),
+    readFile(inputPath, 'utf-8'),
+  ]);
+
+  const monorepo = JSON.parse(monorepoRaw);
+  const content = lodash.template(templateContent)({
     monorepo,
     packages: releasePackages.map(({ name }) => name),
-    encode: (x: string) => global.encodeURIComponent(x),
+    encode: (x: string) => encodeURIComponent(x),
     // Pass-through `ng-dev` ESM commit message information for the `contributing.ejs`
     // template. EJS templates using the devkit template cannot use ESM.
     COMMIT_TYPES: COMMIT_TYPES,
     ScopeRequirement: ScopeRequirement,
   });
-  fs.writeFileSync(outputPath, content, 'utf-8');
+  await writeFile(outputPath, content, 'utf-8');
 }
 
-export default async function (_options: {}): Promise<number> {
+export default async function (): Promise<number> {
   await Promise.all([
-    _runTemplate('./templates/readme.ejs', '../README.md'),
-    _runTemplate('./templates/contributing.ejs', '../CONTRIBUTING.md'),
+    runTemplate('./templates/readme.ejs', '../README.md'),
+    runTemplate('./templates/contributing.ejs', '../CONTRIBUTING.md'),
   ]);
 
   return 0;