Update ESM detection for running fom source and CSS module creation

[aeschli]

This pull request includes changes to improve the detection of ESM(ECMAScript Modules) and the creation of CSS modules. The detect ESM with sources commit updates the ESM detection logic to check if the package.json file has a type field set to module. The only create css modules when needed commit modifies the code to create CSS modules only when necessary, reducing unnecessary requests.