build: allow custom module resolution for ts-circular-deps tests (#36226)

Currently the `ts-circular-deps` tool uses a hard-coded module resolver
that only works in the `angular/angular` repository.

If the tool is consumed in other repositories through the shared
dev-infra package, the module resolution won't work, and a few
resolvable imports (usually cross-entry-points) are accidentally
skipped. For each test, the resolution might differ, so tests can
now configure their module resolution in a configuration file.

Note that we intentionally don't rely on tsconfig's for module
resolution as parsing their mappings rather complicates the
circular dependency tool. Additionally, not every test has a
corresponding tsconfig file.

Also, hard-coding mappings to `@angular/*` while accepting a
path to the packages folder would work, but it would mean
that the circular deps tool is no longer self-contained. Rather,
and also for better flexibility, a custom resolver should be
specified.

PR Close #36226

packages/circular-deps-test.conf.js

@@ -0,0 +1,31 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+const path = require('path');
+
+module.exports = {
+  baseDir: '../',
+  goldenFile: '../goldens/packages-circular-deps.json',
+  // The test should not capture deprecated packages such as `http`, or the `webworker` platform.
+  glob: `./!(http|platform-webworker|platform-webworker-dynamic)/**/*.ts`,
+  // Command that will be displayed if the golden needs to be updated.
+  approveCommand: 'yarn ts-circular-deps:approve',
+  resolveModule: resolveModule
+};
+
+/**
+ * Custom module resolver that maps specifiers starting with `@angular/` to the
+ * local packages folder. This ensures that cross package/entry-point dependencies
+ * can be detected.
+ */
+function resolveModule(specifier) {
+  if (specifier.startsWith('@angular/')) {
+    return path.join(__dirname, specifier.substr('@angular/'.length));
+  }
+  return null;
+}