track_event() mechanism for analytics and plugins

* Closes #2240
* Documentation for event plugin hooks, refs #2240
* Include example track_event plugin in docs, refs #2240
* Tests for track_event() and register_events() hooks, refs #2240
* Initial documentation for core events, refs #2240
* Internals documentation for datasette.track_event()

tests/conftest.py

@@ -1,4 +1,3 @@
-import asyncio
 import httpx
 import os
 import pathlib
@@ -8,7 +7,8 @@ import re
 import subprocess
 import tempfile
 import time
-import trustme
+from dataclasses import dataclass, field
+from datasette import Event, hookimpl
 
 
 try:
@@ -164,6 +164,35 @@ def check_permission_actions_are_documented():
     )
 
 
+class TrackEventPlugin:
+    __name__ = "TrackEventPlugin"
+
+    @dataclass
+    class OneEvent(Event):
+        name = "one"
+
+        extra: str
+
+    @hookimpl
+    def register_events(self, datasette):
+        async def inner():
+            return [self.OneEvent]
+
+        return inner
+
+    @hookimpl
+    def track_event(self, datasette, event):
+        datasette._tracked_events = getattr(datasette, "_tracked_events", [])
+        datasette._tracked_events.append(event)
+
+
+@pytest.fixture(scope="session", autouse=True)
+def install_event_tracking_plugin():
+    from datasette.plugins import pm
+
+    pm.register(TrackEventPlugin(), name="TrackEventPlugin")
+
+
 @pytest.fixture(scope="session")
 def ds_localhost_http_server():
     ds_proc = subprocess.Popen(