Upload a new blob, to be referenced from a repository record.

*This endpoint is part of the atproto PDS repository management APIs. Requests usually require authentication (unlike the `com.atproto.sync.*` endpoints), and are made directly to the user's own PDS instance.* *To learn more about calling atproto API endpoints like this one, see the [API Hosts and Auth](/docs/advanced-guides/api-directory) guide.* Upload a new blob, to be referenced from a repository record. The blob will be deleted if it is not referenced within a time window (eg, minutes)...