feat: add producer connectivity functionality

[nachatz]

Motivation

Expanding async producer support. Some functions are simply missing mappings to the async sibling.

Modifications

Adds producer connectivity functionality to the async producer.

Issue

#278

[BewareMyPower]

is_connected is a wrong legacy design that should not have been added. Actually, it returns false during the reconnection. For example,

• t0: The ownership changed, broker sent a notification to client to disconnect
• t0 + 100 ms: Schedule a new reconnection
• t1: The reconnection was done

is_connected() returns false between [t0, t0 + 100 ms). However, this result is meaningless to users. Users should not do anything for it.

[nachatz]

is_connected is a wrong legacy design that should not have been added. Actually, it returns false during the reconnection. For example,

• t0: The ownership changed, broker sent a notification to client to disconnect
• t0 + 100 ms: Schedule a new reconnection
• t1: The reconnection was done

is_connected() returns false between [t0, t0 + 100 ms). However, this result is meaningless to users. Users should not do anything for it.

Is there a similar option we would want to add around this functionality? Happy to pickup any other async.io tasks to get as much support added ASAP

[BewareMyPower]

I think we can add it in case existing users might already rely on this API. The goal of the asyncio module is to replace the original callback based APIs, so let me reopen it