21.2: Redefining HggPrimaryVertices in HIGG1

Changes to HggPrimaryVertices, the vertex collection used in H->yy analyses. Changes to it are required to allow developments in the HIGG1D1 derivations needed for PFlow: https://its.cern.ch/jira/browse/HGAMSW-716 In specific, the new container is now a shallow copy of PrimaryVertices with redefined vertexType so that the primary vertex is the one selected by the PhotonVertexSelection tool. Decorations are also added to maintain previous functionality. These changes are also be backwards compatible: the name and format of the container is the same, the only practical difference is that the new container contains also pile-up vertices (because it is a shallow copy of PrimaryVertices). Code has been tested in 21.2.84.0.