fix(playwright): separate ESM/CJS loader compilation cache entries fixes 41662

[ahfoysal]

Why

Fixes cache collisions between ESM and CJS loader transforms when loading the same workspace module in both module formats.

What changed

• Use a mode-aware compilation cache key (esm\0filename vs cjs\0filename) for in-memory cache entries.
• Keep existing persisted cache format stable and normalize keys in getUserData() output.
• Add regression test should keep ESM and CJS loader compilation cache separate for workspace modules in tests/playwright-test/loader.spec.ts covering globalSetup + config requiring the same workspace package.

Validation

• npm run -s ttest -- --grep "ESM and CJS" (not runnable here: @playwright/test stable-test-runner module missing)
• npm run -s tsc -- -p packages/playwright/tsconfig.json --pretty false --noEmit (not runnable here: tsc unavailable without local install)

Issue

Fixes #41662

[dgozman]

Decided to not fix this, see issue for more details.