Inline dasherize into strict-resolver.ts, drop the string/ directory

Follow-up to review: with cache.js gone, `string.js` was a 9-line file
exporting just dasherize. Inline it as a private helper in
strict-resolver.ts and delete the strict-resolver/ subdirectory (plus
dasherize_test.js — dasherize's behavior is exercised via
resolver.normalize(...) tests in basic-test.js).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Author: NullVoxPopuli

package.json

@@ -230,7 +230,6 @@
       "@ember/engine/instance.js": "ember-source/@ember/engine/instance.js",
       "@ember/engine/lib/engine-parent.js": "ember-source/@ember/engine/lib/engine-parent.js",
       "@ember/engine/lib/strict-resolver.js": "ember-source/@ember/engine/lib/strict-resolver.js",
-      "@ember/engine/lib/strict-resolver/string.js": "ember-source/@ember/engine/lib/strict-resolver/string.js",
       "@ember/engine/parent.js": "ember-source/@ember/engine/parent.js",
       "@ember/enumerable/index.js": "ember-source/@ember/enumerable/index.js",
       "@ember/enumerable/mutable.js": "ember-source/@ember/enumerable/mutable.js",

packages/@ember/engine/lib/strict-resolver.ts

@@ -1,5 +1,4 @@
 import type { Factory, Resolver } from '@ember/owner';
-import { dasherize } from './strict-resolver/string';
 
 export class StrictResolver implements Resolver {
   // Ember's router uses this flag to decide whether to auto-generate
@@ -130,6 +129,12 @@ export class StrictResolver implements Resolver {
 
 const fileExtension = /\.\w{1,4}$/;
 const leadingDotSlash = /^\.\//;
+const camelCaseBoundary = /([a-z\d])([A-Z])/g;
+const spacesAndUnderscores = /[ _]/g;
+
+function dasherize(str: string): string {
+  return str.replace(camelCaseBoundary, '$1_$2').toLowerCase().replace(spacesAndUnderscores, '-');
+}
 
 type Result =
   | {