Add missing AsyncClient getters and setters for MqttClient properties

[alex-goodisman]

The type definitions claims that AsyncClient extends MqttClient, which implies that all of the public properties present on MqttClient can be accessed on AsyncClient. However, several of the getters and setters are missing. The full list added is:

Properties that had a getter but not setter (setter added):

• connected
• reconnecting

Properties that had neither (both added):

• disconnecting
• disconnected
• incomingStore
• outgoingStore
• options
• queueQoSZero

This will allow the AsyncClient to read and modify these values in the same manner as the base class client.

[alex-goodisman]

The setters may be overkill, but the base mqtt client does allow modifying them in place, so this probably should present the same API. Regardless, it should at least have the missing getters.

[RangerMauve]

Mind updating the index.d.ts typings to match the new properties?