feature: field level file authorization

[Paul-Bob]

Description

Now we can police each file using field level authorization methods.

# app/avo/resources/post_resource.rb
field :cover_photo, as: :file, is_image: true

# app/policies/post_policy.rb
def upload_cover_photo?
  user.student?
end

def download_cover_photo?
  true
end

def delete_cover_photo?
  user.admin?
end

Fixes #1624

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

Docs PR avo-hq/docs.avohq.io#25

[qlty-cloud-legacy]

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[adrianthedev]

The PR looks perfect!
I left a tiny suggestion to make the code easier to understand in the long run.

Thank you!

[github-actions]

This PR has been merged into main. The functionality will be available in the next release.

Please check the release guide for more information.