feat(ng-dev): always require ts-node to be available

As part of our ESM change we should avoid the dynamic import and
just use `ts-node` as a normal import. We expect our ng-dev users
to always have their configs written in TS anyway.

ng-dev/utils/BUILD.bazel

@@ -37,6 +37,7 @@ ts_library(
         "@npm//inquirer",
         "@npm//semver",
         "@npm//supports-color",
+        "@npm//ts-node",
         "@npm//typed-graphqlify",
         "@npm//which",
         "@npm//yaml",

ng-dev/utils/config.ts

@@ -6,6 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import tsNode from 'ts-node';
+
 import {dirname, join} from 'path';
 import {Assertions, MultipleAssertions} from './assertion-typings';
 
@@ -36,9 +38,6 @@ export interface GithubConfig {
  */
 const CONFIG_FILE_PATH = '.ng-dev/config';
 
-/** The configuration for ng-dev. */
-let cachedConfig: {} | null = null;
-
 /**
  * The filename expected for local user config, without the file extension to allow a typescript,
  * javascript or json file to be used.
@@ -147,23 +146,15 @@ export function assertValidGithubConfig<T>(
  * configuration file cannot be read.
  */
 function readConfigFile(configPath: string, returnEmptyObjectOnError = false): {} {
-  // If the `.ts` extension has not been set up already, and a TypeScript based
-  // version of the given configuration seems to exist, set up `ts-node` if available.
-  if (
-    require.extensions['.ts'] === undefined &&
-    existsSync(`${configPath}.ts`) &&
-    isTsNodeAvailable()
-  ) {
-    // Ensure the module target is set to `commonjs`. This is necessary because the
-    // dev-infra tool runs in NodeJS which does not support ES modules by default.
-    // Additionally, set the `dir` option to the directory that contains the configuration
-    // file. This allows for custom compiler options (such as `--strict`).
-    require('ts-node').register({
-      dir: dirname(configPath),
-      transpileOnly: true,
-      compilerOptions: {module: 'commonjs'},
-    });
-  }
+  // Ensure the module target is set to `commonjs`. This is necessary because the
+  // dev-infra tool runs in NodeJS which does not support ES modules by default.
+  // Additionally, set the `dir` option to the directory that contains the configuration
+  // file. This allows for custom compiler options (such as `--strict`).
+  tsNode.register({
+    dir: dirname(configPath),
+    transpileOnly: true,
+    compilerOptions: {module: 'commonjs'},
+  });
 
   try {
     return require(configPath);