RDKB-41431 : service_dhcpv6_client.sh C conversion
RDKB-41431 : service_dhcpv6_client.sh C conversion

Reason for change: service_dhcpv6_client.sh C conversion
Test Procedure: dibbler Client should comeup properly and no new regressions should be caused
Risks: Low
Signed-off-by:BudimeVigneshwar_Prasad@comcast.com

(cherry picked from commit 5a5afd38d38164d80fd54e2ed3989b30cb42989a)

RDKB-44197 : core net lib exception for service_dhcpv6_client

Reason for change: Adding core net lib exception for service_dhcpv6_client handling
Test Procedure: service_dhcpv6_client handling should not be working for core_net_lib disabled devices
Risks: Low
Signed-off-by:BudimeVigneshwar_Prasad@comcast.com

Change-Id: I352e0f88a2889bd2f995688b91afcecec53b3030

rdkcmf/rdkb-CcspPandM,rdkcmf/rdkb-CcspPandM,rdkcmf/rdkb-CcspPandM