PersistentDataModel, etc: Embed Token in DataHeaderElement.

Embed Token by DataHeaderElement by value rather than holding it as a pointer, to reduce the number of memory allocations needed and speed things up slightly.

This merge request affects 4 packages:

• Database/PersistentDataModel
• Database/PersistentDataModelAthenaPool
• Database/PersistentDataModelTPCnv
• Event/ByteStreamCnvSvc

Affected files list will not be printed in this case

Adding @maszyman ,@tadej ,@gemmeren ,@mnowak ,@ssnyder ,@amete as watchers

added Database EDM main review-pending-level-1 labels

CI Result SUCCESS (hash f6dcabb2)

	Athena	AthSimulation	AthGeneration	AthAnalysis
externals
cmake
make
tests

Full details available on this CI monitor view. Check the JIRA CI status board for known problems
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AthAnalysis: number of compilation errors 0, warnings 0
For experts only: Jenkins output (remote access info)

Changes are fine and CI succeeds, approving for L1. -L1

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit ead0689d