Implement a downstream load/save handler in `revng.internal.api.Manager`
class which handles loading and saving files from a local directory to
a s3 server.
Package revng's python code in two wheels: `revng` and `revng_internal`.
The revng wheel contains the
`revng.{pipeline_description,model,tupletree}` modules, while the
`revng_internal` one everything under `revng.internal`.
Giacomo Vercesi