abandon eventlet

[4383]

Here is an issue to track the different steps to progressively abandon Eventlet.
The goal of this github issue is to:

1. define the various steps
2. track the advancement

Steps

• describe the various alternatives to eventlet into the migration guide
• describe how to migrate a single deliverable
• deprecate the hubs who are not the AsyncIO hub
• stop adding support to hubs who are not the AsyncIO hub
• announce the coming abandon on the documentation and on the github readme
• abandon Eventlet by archiving the github repo

[4383]

Will update the main description to keep this plan synced