GH-3822 Allow MQTTv5 reconnection, even when first connection fails

[kroutal]

GH-3822: Allow MQTTv5 reconnection, even when first connection fails

[artembilan]

There are some Checktyle violations:

 Error: eckstyle] [ERROR] /home/runner/work/spring-integration/spring-integration/spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapter.java:168:17: '}' at column 3 should be alone on a line. [RightCurly]
Error: eckstyle] [ERROR] /home/runner/work/spring-integration/spring-integration/spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapter.java:172:33: '}' at column 5 should be alone on a line. [RightCurly]
Error: eckstyle] [ERROR] /home/runner/work/spring-integration/spring-integration/spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapter.java:175:25: '}' at column 4 should be alone on a line. [RightCurly]
Error: eckstyle] [ERROR] /home/runner/work/spring-integration/spring-integration/spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/outbound/Mqttv5PahoMessageHandler.java:176:25: '}' at column 4 should be alone on a line. [RightCurly]

Please, run this command locally ./gradlew clean :spring-integration-mqtt:check

[artembilan]

Here is my further review.

Thank you!

[artembilan]

Merged as 8cf5f90 and cherry-picked to 5.5.x after some clean up and minor tests & docs improvements.

@kroutal ,

thank you very much for the contribution; looking forward for more!