feature: Attachments

[batuhan]

Use TransloadIt for uploads, after an upload the objects will be moved our S3 object storage and will be added to the attachments table to get an attachment ID that corresponds to a path key in a bucket.

We already have Uppy working as the upload client but it needs some integration to both Tina and ProseMirror (document editor) -- shouldn't be too hard as it's mostly writing a wrapper that passes some data around.

This ties into #17

[batuhan]

This is almost done but works unreliable as fuck. Will refactor with better knowledge of wix editor

[batuhan]

Type of attachments:

• files (in asset deliverables)
• single image (everywhere)
• gallery (everywhere)
• video (embed everywhere but upload in asset deliverasbles only)