Improve interfacing with gofer

[ckoopmann]

Currently we interface with the gofer tool by executing a cli command from rust.
This is inefficient as well as brittle and probably should be changed.

One way to do it would be to call the json_rpc endpoint of the gofer agent service.
In this context we should also revisit the handling of gofer configuration / customization which is currently saved in config.hcl in the top level of this repo.