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 
I *could*, but that would require me to format the generated xml in the tests, which gets messy. Tbh, I need to refactor the tests that use these, as they rely on plain ol' string comparison, which is clunky and very error prone/hard to debug. So I'm planning on refactoring to do a better comparison to this data, at which point I should be able to format the files for readability.