The module fallback of vitest-pool-work looks for required files adding js extensions

This behavior is specific to require (see doc) but should not be used for imports. Then we should only it when the resolve method is === "require".

One caveat is that TS extend the import spec and allow not to specify and specify any extension depending on the tsconfig setting - how do we want to handle that?

Note: #11917 (pending ATM) is correctly adding.json to the list.