Support for Different File Data Sources

[afolarin]

Currently, the preferred data source is a relational DB with documents included as BLOBs but there are other possible sources, but some are less needed to be supported at present. I've ranked them based on how likely I expect these to be encountered.

• 1. BLOBs in database
• 2. Pointers to file paths on a filesystem (or object store)
• 3. Files on Filesystem with metadata e.g. patientID in Filename or File contents
• 4. Object Store (e.g. S3 or other) with metadata e.g. patientID in object metadata labels