* add '-DvalueAsATopic=true' to RF based environments
add '-DvalueAsATopic=true' to RF based environments. Required to support changes in zgatewayRF.ino for Home Assistant discoverability
* Modify gatewayRF to improve Home Assistant auto discoverability
Pass "recieved" as the type argument and switchRF[0] as the subtype argument to announceDeviceTrigger() which will cause recieved codes to be picked up by home assistant as triggers, i.e. When setting up automations in Home Assistant, selecting a `device` trigger and an OMG device will allow the user to select a code picked up during the autoDiscover window as the trigger for the automation, for example "1394004" recieved. In order to support this, the `'-DvalueAsATopic=true'` argument must be added to all environments using the RF Library
Also change getUniqueId() call to remove leading '-' which will prevent MQTT topics having '--' in them
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Co-authored-by: James Carey <james.carey@uws.ac.uk>
