Mbst 9820 youview initial output

 - Refactor of logic around which elements are output for a given piece of content
 - Improved testing
 - Refactor of flags to allow enabling of test endpoints separately from upload feed tasks for each publisher's upload
 - Initial version of transaction store - stores content ids against transaction id per publisher, and has a placeholder for a transaction status
 - Initial version of an BroadcastEventGenerator, with hardcoded fields where values are unknown/not yet ingested from NITRO 
maybe Mockito static methods could be statically imported