Ability to expedite reconnect

- [N] Bug exists Release Version 1.2.0 ( Master Branch)
- [N] Bug exists in MQTTv3 Client on Snapshot Version 1.2.1-SNAPSHOT (Develop Branch)
- [N] Bug exists in MQTTv5 Client on Snapshot Version 1.2.1-SNAPSHOT (Develop Branch)
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It's not a bug, It's a gentle feature request :)

Currently Paho client tries to reconnect in double raised intervals if configured to automatically reconnect which is nice. It would be very useful if library clients could expedite this process, so make reconnect happen sooner if application internet came back after a long time, instead of waiting for 128 seconds.

I changed paho client[ to do so](https://github.com/eclipse/paho.mqtt.java/compare/master...reith:1.2.507) and I think it works fine and is nice to have it in library. What do you think?

Thanks