Implement support to serve media from private buckets

[syphernl]

Which part of the project should be enhanced?

Media Uploads

Is your enhancement request related to a problem? Please describe.

No response

Describe the solution you'd like

Media uploaded to buckets, e.g. S3, require the buckets (and their objects) to be available publicly. It would be preferable to keep a bucket set to private.

Describe alternatives you've considered

A few ideas to implement this:

• Use signed urls (but they expire so they cannot be stored as-is).
• Create a "media proxy" endpoint that retrieves the image from the bucket. It could return either the signed URL (or redirect to it) or the actual object it obtained.

Additional context

No response

[ErikMichelson]

An endpoint for media access is tracked in #2310 and currently being implemented in #5535. The endpoint will redirect to the URL that the configured storage backend returns.

Making the S3 storage backend return signed URLs is a feature I'd like to see as well. Issue #2104 has some similarities, although not being the same thing.