Add logger

[rdettai]

Replace println calls with Tracing (by tokio).

Cf experiements on the logger feat branch.

Objectives:

• make the logs easily parseable (json likely the best for that)

This is less critical if #4 is implemented.

[Michael-J-Ward]

Are you accepting contributors?

[rdettai]

sure! This project has not moved for the past few months because I am trying to re-structure the approach:

• I extracted the reader that fetches chunks from S3 into a specific library: https://github.com/cloudfuse-io/cloud-readers-rs
• I am trying to run ballista in the cloud in different forms: https://github.com/cloudfuse-io/ballista-aws-tools

One breakthrough that might happen is if we manage to run Ballista directly in lambda functions thanks to TCP whole punching: https://vtechworks.lib.vt.edu/bitstream/handle/10919/103627/Moyer_DW_T_2021.pdf?sequence=1 In that case, the design of Buzz could be simplified a lot! Instead of having HCombs to act as reducers, HBees could communicate directly together! We wond only need one server that takes care of doing the hole puncing!