Unify Dashboard & Webhook events (#394)

This change unifies the previously adhoc SignalR events and Webhooks into a single event format.

src/api-service/__app__/onefuzzlib/events.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+#
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+
+import json
+import logging
+from queue import Empty, Queue
+from typing import Optional
+
+from onefuzztypes.events import Event, EventMessage, get_event_type
+
+from .webhooks import Webhook
+
+EVENTS: Queue = Queue()
+
+
+def get_events() -> Optional[str]:
+    events = []
+
+    for _ in range(5):
+        try:
+            event = EVENTS.get(block=False)
+            events.append(json.loads(event.json(exclude_none=True)))
+            EVENTS.task_done()
+        except Empty:
+            break
+
+    if events:
+        return json.dumps({"target": "events", "arguments": events})
+    else:
+        return None
+
+
+def send_event(event: Event) -> None:
+    event_type = get_event_type(event)
+    logging.info("sending event: %s - %s", event_type, event)
+    event_message = EventMessage(event_type=event_type, event=event)
+    EVENTS.put(event_message)
+    Webhook.send_event(event_message)