Support attachment meta, fixes #1828
Downstream MR: https://gitlab.com/soapbox-pub/soapbox/-/merge_requests/18
- Adds an optional upload filter,
Pleroma.Upload.Filter.SetMeta
, which stores the dimensions (length x width) of an upload. - If upload dimensions are available, they are now federated (in both directions).
- If upload dimensions are available, MastoAPI will render the
meta
section of an attachment, and return those values.