Add packable types for VP & FT clusters and converters
Adds a first version of what could be the packing/unpacking of VPLightClusters as well as FTLiteClusters. For the VPLightClusters, this is achieved by using a minimal type (VPMicroCluster), which erases the global coordinates. For the FTLiteClusters, an additional wrapper is built to make sure it gets a CLID, needed by the packing.
There are tests that confirm the validity of the location information based on the packed info in the related MRs.
Goes with Moore!2670 (closed) and Rec!3597 (closed)