Support fix-path in non-bundled environments

[msujew]

What it does

Closes #14804

Adjusts the import of fix-path to ensure that it also works in non-bundled environments.

How to test

1. Adjust the electron test app: Replace the main entry in the package.json with "src-gen/backend/electron-main.js".
2. Run npm run build:electron && npm run start:electron
3. The app still doesn't start due to other ESM dependencies, but at least it gets to import them ¯\_(ツ)_/¯

Follow-ups

We should switch to ESM modules in our app.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines