Refactors bigip_selfip (#31732)

In this refactor we moved to the most recent coding standards for
both F5 and Ansible. Many bugs were fixed and some features were
also added (such as ipv6 support).

test/units/modules/network/f5/fixtures/load_tm_net_self.json

@@ -0,0 +1,26 @@
+{
+  "kind": "tm:net:self:selfstate",
+  "name": "net1",
+  "partition": "Common",
+  "fullPath": "/Common/net1",
+  "generation": 7,
+  "selfLink": "https://localhost/mgmt/tm/net/self/~Common~net1?ver=13.0.0",
+  "address": "10.10.10.10%1/24",
+  "addressSource": "from-user",
+  "floating": "disabled",
+  "inheritedTrafficGroup": "false",
+  "trafficGroup": "/Common/traffic-group-local-only",
+  "trafficGroupReference": {
+    "link": "https://localhost/mgmt/tm/cm/traffic-group/~Common~traffic-group-local-only?ver=13.0.0"
+  },
+  "unit": 0,
+  "vlan": "/Common/net1",
+  "vlanReference": {
+    "link": "https://localhost/mgmt/tm/net/vlan/~Common~net1?ver=13.0.0"
+  },
+  "allowService": [
+    "tcp:80",
+    "udp:53",
+    "gre:0"
+  ]
+}