* Internal: cleanup Networking V2 Ports

Add StateRefreshFunc(), expandNetworkingPortFixedIpsV2 into the
"networking_port_v2.go".

Change "fixed_ip" argument type to "TypeSet".

Use "expandToStringSlice()" function to retrieve "security_groups"
value. This change also affects "openstack_lb_loadbalancer_v2" resource
code.

Add common "boolPtrArgument()" into "util.go" to work with some special
arguments like "admin_state_up".

Fix debug and error messages.

* Internal: Use TypeSet for Ports V2 all_fixed_ips

We should remove dependency of ordering of the IPs inside the
"all_fixed_ip" attribute for openstack_networking_port_v2 resource and
datasource.

* Networking V2 Port IDs data: fix securityGroups

Use expandToStringSlice() for getting securityGroups in the
"data_source_openstack_networking_port_ids_v2".

* Networking V2 ports: revert all_fixed_ips TypeSet

Leave TypeList for "all_fixed_ips" argument in the
openstack_networking_port_v2 resource and datasource.

* Networking V2: cleanup ports datasources messages

Use "openstack_networking_port_v2" as object name for the
openstack_networking_port_ids_v2 and openstack_networking_port_v2
datasources.

* Util: remove boolPtrArgument()

Remove boolPtrArgument() as it won't be used.

* Networking V2 Port: use TypeList for fixed_ip

Use TypeList for "fixed_ip" argument and add tests for the
expandNetworkingPortFixedIPV2() helper function.

* Networking V2 Ports: return addr pairs hash

Use custom resourceNetworkingPortV2AllowedAddressPairsHash() function
for "allowed_address_pairs" set.