Rego functions for cache write and read

Implement Rego built-in functions for accessing the TSA cache.

added Backlog label

assigned to @lyuben.penkovski

changed milestone to %Sprint 6

removed Backlog label

added DevInProgress label

mentioned in merge request !11 (merged)

mentioned in commit e0453d30

mentioned in commit 0ec7620c

closed with merge request !11 (merged)