Improve IPV6 parity in Security Group testcases

This patch implements positive and negative IPV6 testcases
for Security Groups and adds few additional test cases to
validate icmp protocol, remote_group_id and remote_ip_prefix

Change-Id: I3dd272f15a282b2ac58beee10f36c8af66377727
Partially implements: bp ipv6-api-testing-parity
Merge "Improve IPV6 parity in Security Group testcases"