Implement the generation and transmission of a manifest file for a transfer

[jeff-cohere]

We've decided that a manifest file is to be generated for each file transfer.

• The manifest is a JSON file that implements a Frictionless Data Package.
• The manifest describes the contents of the transfer's payload.
• The manifest is generated by the DTS when the transfer operation is created.
• Not clear yet how the manifest makes its way to the destination endpoint (perhaps DTS needs its own endpoint?). Maybe Globus Flows can help with this?