add SylvaUnitsReleaseTemplate CRD
/cc @priyagoyal @feleouet
follow up to workload-cluster-operator!3 (comment 1682565110)
This MR adds a SylvaUnitsReleaseTemplate CRD.
This is a simple static CRD that has the same spec as a SylvaUnitsRelease, without any specific controller behavior.
It is used by workload-cluster-operator!19 (merged) to built a SylvaUnitsRelease based on its content.
Edited by Thomas Morin