feat: replace event channel with broadcast channel

This makes `EventTracker` receive events immediately
instead of being moved from event emitter to event tracker
by a task spawned from `TestContext::new_internal`.

This makes `EventTracker.clear_events` reliable
as it is guaranteed to remove all events emitted
by the time it is called rather than only events
that have been moved already.

deltachat-ffi/deltachat.h

@@ -362,8 +362,12 @@ uint32_t        dc_get_id                    (dc_context_t* context);
  *     Must be freed using dc_event_emitter_unref() after usage.
  *
  * Note: Use only one event emitter per context.
- * Having more than one event emitter running at the same time on the same context
- * will result in events being randomly delivered to one of the emitters.
+ * The result of having multiple event emitters is unspecified.
+ * Currently events are broadcasted to all existing event emitters,
+ * but previous versions delivered events to only one event emitter
+ * and this behavior may change again in the future.
+ * Events emitted before creation of event emitter
+ * may or may not be available to event emitter.
  */
 dc_event_emitter_t* dc_get_event_emitter(dc_context_t* context);
 

deltachat-ffi/src/lib.rs

@@ -4922,7 +4922,9 @@ mod jsonrpc {
         }
 
         let account_manager = &*account_manager;
-        let cmd_api = deltachat_jsonrpc::api::CommandApi::from_arc(account_manager.inner.clone());
+        let cmd_api = block_on(deltachat_jsonrpc::api::CommandApi::from_arc(
+            account_manager.inner.clone(),
+        ));
 
         let (request_handle, receiver) = RpcClient::new();
         let handle = RpcSession::new(request_handle, cmd_api);