Inline used @ember/string methods directly

[lifeart]

After ember@5 - ember-resolver is only one "bundled" dependency with @ember/string.

This ticket is created to follow on @ember/string deprecation.

We need to inline @ember/string methods here (used in resolver).

https://github.com/emberjs/ember-string/blob/master/addon/index.ts

https://github.com/ember-cli/ember-resolver/blob/main/addon/addon/index.js#L6

[lifeart]

In addition, it seems very valid to have infinity cache (https://github.com/emberjs/ember-string/blob/master/addon/cache.ts) here for resolver (because amount of items is finite) to not trigger gc in large ember applications during loading/components rendering.

upd: it's better to move @ember/string as is (for now)