Support more formats for packing blobs

[dehann]

Possible examples (identified by mimeType in the Entry):

• JSON
• parquet
• arrow
• ...?

[Affie]

We currently have these:

• JSON: "application/octet-stream/json"
• BSON: "application/bson"
• PNG: "image/png"
• JPG: "image/jpeg"
• LAS: "application/octet-stream; ext=las" (maybe rename to "application/vnd.las")

We can add:

• [ ] ARROW: "application/vnd.apache.arrow.file"
• [ ] PARQUET: "application/vnd.apache.parquet"