feat: add db query for setting interception ended_at field (#20437)

Adds UpdateAIBridgeInterceptionEnded query to mark interceptions as
done.
Needed for https://github.com/coder/internal/issues/1051

docs/reference/api/aibridge.md

@@ -31,6 +31,7 @@ curl -X GET http://coder-server:8080/api/v2/api/experimental/aibridge/intercepti
   "count": 0,
   "results": [
     {
+      "ended_at": "2019-08-24T14:15:22Z",
       "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",
       "initiator": {
         "avatar_url": "http://example.com",