From monolith to micro-service model

[nrybowski]

Is your feature request related to a problem? Please describe.
INGInious is currently implemented and deployed as a monolith while it is designed as a distributed infrastructure.
The installation of the different components may be difficult on some platforms due to variations in packaged version of required libraries. See e.g. #873.

Describe the solution you'd like
INGInious should be packaged, distributed and deployed as a set of micro-service because:

• It solves dependencies issues, e.g. MongoDB is not packaged in the official Ubuntu repos. We rather pull the latest container image.
• It allows easier deployment with tools such as docker-compose or Terraform.
• It allows easier scaling by duplicating given services according to the load requirements.

Additional context
A special attention should be payed to Agents (e.g. the Docker Agent) requiring access to a docker daemon. Solutions as the daemonless OCI platform Podman could be envisioned to avoid leaking docker sockets within the Agent containers. That would require a small interface to talk with its REST API.