Support webapp to render post rapidly for bot without additional call for user/bot. (#10793)

app/post.go

@@ -166,6 +166,10 @@ func (a *App) CreatePost(post *model.Post, channel *model.Channel, triggerWebhoo
 		return nil, err
 	}
 
+	if user.IsBot {
+		post.AddProp("from_bot", "true")
+	}
+
 	if a.License() != nil && *a.Config().TeamSettings.ExperimentalTownSquareIsReadOnly &&
 		!post.IsSystemMessage() &&
 		channel.Name == model.DEFAULT_CHANNEL &&