Add code quality to the project

See merge request !149

Merge previous default branch feat-cod-rmq into main

See merge request rc/rabbitmq_agents!147

Add account creation flowchart

See merge request !148

Update black version

Use a new variable to send the notification email to users for their …

Adding a new variable to define the from address for subscription email

Support for 3.6 has been dropped from this conversation: https://github.com/actions/setup-python/issues/544

Add greenlet in requirements

Refactor ssh access agent

User would be removed from one or more groups according to the
list provided in msg, before they are added to one or more groups.

This change will support our design decision that a user should be only
part of a group that corresponds to his current state. Users are not in
two states at any given time, they have only one state. Likewise, they
should only be in one group at a time corresponding to their state (look
at rabbit_config.py)

Previously to block ssh access, user is put in nossh group by ssh_access
agent. This new design will make use of group_member agent that is part
of group management framework which puts a user in a group list provided.