support: $queue/<topic> for sharing subscribe

[elvizlai]

As EMQX mentioned.

It allows load balancing between multiple subscribers in the same group when distributing MQTT messages.

                            -----------
                            |         | --Msg1--> Subscriber1
Publisher--Msg1,Msg2,Msg3-->|  EMQ X  | --Msg2--> Subscriber2
                            |         | --Msg3--> Subscriber3
                            -----------

Prefix	Examples
$queue/	mosquitto_sub -t ‘$queue/topic’
$share/<group>/	mosquitto_sub -t ‘$share/group/topic’

This PR fix $share/ prefix and add $queue support.

[elvizlai]

Sorry, hidden@gmail.com is not recognized as a user name or an email address.

??? can not sign.

[alsm]

You need to have an eclipse account with the same email and have signed the CLA for the check to pass

[elvizlai]

CLA signed

[alsm]

Thanks