Rename resource pool allocation IPv6 roles

[chrismarget-j]

The apstra_datacenter_resource_pool_allocation resource supports the following values in the role attribute:

• access_asns
• access_l3_peer_link_link_ips
• access_loopback_ips
• evpn_l3_vnis
• generic_asns
• generic_loopback_ips
• generic_loopback_ips_ipv6
• ipv6_spine_leaf_link_ips <<----------- this one
• ipv6_spine_superspine_link_ips <<---- this one
• ipv6_to_generic_link_ips <<----------- this one
• leaf_asns
• leaf_l3_peer_links
• leaf_l3_peer_links_ipv6
• leaf_leaf_link_ips
• leaf_loopback_ips
• leaf_loopback_ips_ipv6
• mlag_domain_svi_subnets
• mlag_domain_svi_subnets_ipv6
• spine_asns
• spine_leaf_link_ips
• spine_loopback_ips
• spine_loopback_ips_ipv6
• spine_superspine_link_ips
• superspine_asns
• superspine_loopback_ips
• superspine_loopback_ips_ipv6
• to_generic_link_ips
• virtual_network_svi_subnets
• virtual_network_svi_subnets_ipv6
• vni_virtual_network_ids
• vtep_ips

Three of those values don't quite fit in. To fit in with the pattern established by the other values, they should be:

• ipv6_spine_leaf_link_ips_ipv6
• ipv6_spine_superspine_link_ips_ipv6
• ipv6_to_generic_link_ips_ipv6