EventMgr: Add Dispatch() with handler and args

Allow users to call event_mgr.Dispatch(handler, args) instead of
constructing the Event instance themselves. Deprecate the old API
and replace users.

There's a subtle change that net_done() may be propagated via
auto_publish() now, but that still needs opt-in from script land
and likely no one did that, or else they'd expected to have it
work anyhow.

src/Event.h

@@ -80,8 +80,15 @@ public:
         return Enqueue(h, zeek::Args{std::forward<Args>(args)...});
     }
 
+    [[deprecated("Remove in v8.1: Use Dispatch(handler, args) instead.")]]
     void Dispatch(Event* event, bool no_remote = false);
 
+    // Dispatch an event with the given handler and arguments immediately.
+    //
+    // While the event is technically not queued, HookQueueEvent() is
+    // invoked on the Event instance regardless.
+    void Dispatch(const EventHandlerPtr& h, zeek::Args vl);
+
     void Drain();
     bool IsDraining() const { return current != nullptr; }