[ATR-21373] Trigger JSON menu metadata storage and access. EDM Part
This is the first half of !32844 (closed) (which will be used only for CI, and hence closed in the future).
This MR introduces the new TriggerMenuJson
XAOD object.
This is a simple store of a (string serialised) JSON blob, and a single numeric key used to associate this blob with its database entry.
Unlike for the R2 format where the whole menu was packed into a single object, we have one TriggerMenuJson
collection per JSON blob from the DB.
It is expected to have blobs for: HLT menu, L1 menu, HLT prescales, L1 prescales, BG pattern.
(There is also the HLT setup file, but this is not classified as metadata and won't be stored in in-file metadata)
The MR to use these new EDM objects will be added once this is merged.