VPP-547: Fix for co-existence of HbH and RH header in Segment routing:

VPP-547: Fix for co-existence of HbH and RH header in Segment routing:

1. sr-rewrite - SR insertion in v6 : SR RH is inserted immediately after v6 header
but if hbh header is present as per RFC2460 it should immediately follow
v6 header. This is fixed.
2. sr-local : v6 packet destined to a sr segment is received if hbh is present
it is not handed over to sr-local for processing. fixed ip6-local handling to
skip hbh as there is no register handler for hbh for now.
3. sr-replicate - update in dual of sr_rewrite to handle replicate, fixes in
sr-replicate to handle presence of hbh header

Change-Id: I034523a42d2fedf97134761f956ab534babb8b36
Signed-off-by: Shwetha <shwethab@cisco.com>