[FEATURE] argilla: add support to create image fields

[frascuchon]

Description

This PR adds support to work with image fields using the SDK.

TODO (as separate PRs)

• Add documentation section
• Verify behavior using from/to_hub methods
• Add tooling to read data URLs from image files/folders (based on logic defined in image_to_html)
• Add some media type validation (supported image types)
• [Optional] Add tooling to re-scale images. The lower the image sizes, the better the UI work. We can define a transparent re-scaling process to support large images (currently the limit size in the backend is 5MB for data URL)

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested

Checklist

• I added relevant documentation
• I followed the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• I confirm My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)