Make BotJoinGroupEvent.Active and .Invite inherit BotJoinGroupEvent

[yyuueexxiinngg]

让BotJoinGroupEvent.Active, BotJoinGroupEvent.Invite事件继承BotJoinGroupEvent

目前, 下方测试代码中第一个whenblock不会被触发, 而类似事件如MemberJoinEvent中Invite和Active都继承了其父类, 所以类似block可以正确触发

        bot.subscribeAlways<BotEvent> {
            when (this) {
                is BotJoinGroupEvent -> {
                    println("Bot Join Event !!!!!!!!!!!!!!!")
                    when (it) {
                        is BotJoinGroupEvent.Active -> println("1: Bot joined group: ${group.name}")
                        is BotJoinGroupEvent.Invite -> println("1: Bot joined group by invitation! Group: ${group.name}")
                    }
                }
                is BotJoinGroupEvent.Active -> println("2: Bot joined group: ${group.name}")
                is BotJoinGroupEvent.Invite -> println("2: Bot joined group by invitation! Group: ${group.name}")
            }
        }