Adding sTGC xAOD PRD output
As with !69514 (merged), this adds the ability for the RDO to PRD convertor to output xAOD PRDs directly, and adds them to the test.
There is some missing functionality, since:
- we do not have access to the ReadoutElement
- I do not yet know how to handle merging xAOD PRDs
This will come in follow up MRs. This is all disabled by default.
cc @jojungge