新增 firebase cloud message 消息推送 (#236)

* 新增 firebase cloud message 消息推送

新增 api接口  /third/fcm_update_token 用于更新客户端获取到 FCM token 同步到服务器

* mongodb授权缺少授权数据库

windows下面的编译+启动

internal/push/logic/init.go

@@ -8,6 +8,7 @@ package logic
 
 import (
 	pusher "Open_IM/internal/push"
+	fcm "Open_IM/internal/push/fcm"
 	"Open_IM/internal/push/getui"
 	jpush "Open_IM/internal/push/jpush"
 	"Open_IM/pkg/common/config"
@@ -41,6 +42,10 @@ func init() {
 	if config.Config.Push.Jpns.Enable {
 		offlinePusher = jpush.JPushClient
 	}
+
+	if config.Config.Push.Fcm.Enable {
+		offlinePusher = fcm.FcmClient
+	}
 }
 
 func Run() {