BPF filter support

Fix https://github.com/GNS3/gns3-gui/issues/765

tests/controller/test_link.py

@@ -369,9 +369,10 @@ def test_update_filters(async_run, project, compute):
     link.update = AsyncioMagicMock()
     assert link._created
     async_run(link.update_filters({
-        "packet_loss": ["10"],
-        "delay": ["50", "10"],
-        "frequency_drop": ["0"]
+        "packet_loss": [10],
+        "delay": [50, 10],
+        "frequency_drop": [0],
+        "bpf": [" \n  "]
     }))
     assert link.filters == {
         "packet_loss": [10],

tests/controller/test_udp_link.py

@@ -373,11 +373,14 @@ def test_update(async_run, project):
     }, timeout=120)
 
     assert link.created
-    async_run(link.update_filters({"drop": [5]}))
+    async_run(link.update_filters({"drop": [5], "bpf": ["icmp[icmptype] == 8"]}))
     compute1.put.assert_any_call("/projects/{}/vpcs/nodes/{}/adapters/0/ports/4/nio".format(project.id, node1.id), data={
         "lport": 1024,
         "rhost": "192.168.1.2",
         "rport": 2048,
         "type": "nio_udp",
-        "filters": {"drop": [5]}
+        "filters": {
+            "drop": [5],
+            "bpf": ["icmp[icmptype] == 8"]
+        }
     }, timeout=120)