Add `group` and `senderName` shortcuts to `TempMessage`

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/TempMessage.kt

 package net.mamoe.mirai.message
 
 import net.mamoe.mirai.Bot
+import net.mamoe.mirai.contact.Group
 import net.mamoe.mirai.contact.Member
+import net.mamoe.mirai.contact.nameCardOrNick
 import net.mamoe.mirai.event.BroadcastControllable
 import net.mamoe.mirai.message.data.MessageChain
 import net.mamoe.mirai.message.data.MessageSource
@@ -27,6 +29,8 @@ class TempMessage(
     override val sender: Member by sender.unsafeWeakRef()
     override val bot: Bot get() = sender.bot
     override val subject: Member get() = sender
+    inline val group: Group get() = sender.group
+    inline val senderName: String get() = sender.nameCardOrNick
     override val source: OnlineMessageSource.Incoming.FromTemp get() = message.source as OnlineMessageSource.Incoming.FromTemp
 
     override fun toString(): String =