Added default sdkconfig for qemu build for the mqtt publish example,
Added environment configuration for running the same test on target
or in qemu
Updated missing example tests per latest ttfw refactoring
The MQTT broker URL used as default in the examples has ceased operation. All examples and documention have been updated to point to the new domain mqtt.eclipse.org.
This also required an update of the python example test scripts to use TLS 1.2