Add init script for Playwright browser context

[vdusek]

• For now, let's use a data file containing fingerprints (or at minimum user agents) from the Apify fingerprint dataset.
• Use the init script from the fingerprint suite.
• A fingerprint, selected based on parameters such as OS or browser type, should be passed to the init script.
• Load the JS init script from a file and convert it into a string for injection.
• Inject the script into the Playwright browser context using BrowserContext.add_init_scripts().
• Possible inspiration:
  • undetected-playwright-python,
  • playwright_stealth.