SRv6 policy models fixes:

• binding-sid_config grouping contains value with type of uint32, which represents MPLS label only. It was changed to sid-value-type which represents both MPLS label and SID definition.
  This issue was reported and will be fixed in next version of the model.
• leaf-ref preference in candidate-path list had bad pointer to config/name leaf, this was fixed to point correctly to config/preference.
  This issue was reported and will be fixed in next version of the model.
• pce-peer in pcc grouping contains address leafref to config/address, but configuration params were not  encapsulated in config container.
  This issue was reported, awaiting feedback.