Added Anchorbrowser computer implementation

[guybensimhon1]

We're adding Anchorbrowser as a new browser environment for CUA. This PR introduces the AnchorBrowser class as a new Computer implementation.

Key Changes:

• Added AnchorBrowser class inheriting from BasePlaywrightComputer.
• Implemented all required Computer interface methods.
• Added configuration using ANCHOR_API_KEY.
• Updated CLI to include the Anchor option.

Next Steps:
We already support OS-like features for viewing and clicking, similar to Operator, and plan to integrate these for a seamless Operator-like interface. We'll keep this integration updated with improvements from both CUA and Anchorbrowser.

Questions?
Let us know if you have any questions or need changes. You can reach us at hi@anchorbrowser.io.

[ibigio]

tl;dr please adhere to new computer structure and contributing process

Hi! Thanks for your contribution – we'd love to get it reviewed and merged. To better support custom CUA computers we've created a contrib directory to co-locate community contributions and automatically run basic smoke tests.

Please make sure you complete the three main steps:

1. Move computers/contrib and update configs
2. Pass tests & do manual testing
3. Submit PR with required information

These are explained in detail in the contributing section of the README.

Thanks again!

[GDanksAnchor]

Hey @ibigio, we created this pull request instead, to adhere with the contribution process.

If you could check it out, and let us know if something needs further improvements.
Thanks a lot for your time.