Remove `@Serializable` from core module

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

@@ -12,8 +12,9 @@
 package net.mamoe.mirai.message.data
 
 import kotlinx.io.core.*
-import kotlinx.serialization.*
-import kotlinx.serialization.builtins.ByteArraySerializer
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.UnstableDefault
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonConfiguration
 import kotlinx.serialization.protobuf.ProtoBuf
@@ -35,7 +36,6 @@ import kotlin.jvm.JvmOverloads
  *
  * @see CustomMessageMetadata 自定义消息元数据
  */
-@Serializable(with = CustomMessage.MessageSerializer::class)
 @MiraiExperimentalAPI
 sealed class CustomMessage : SingleMessage {
     /**

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

@@ -22,6 +22,7 @@ import net.mamoe.mirai.utils.MiraiExperimentalAPI
 import net.mamoe.mirai.utils.currentTimeSeconds
 import kotlin.jvm.JvmOverloads
 import kotlin.jvm.JvmSynthetic
+import kotlin.jvm.Transient
 
 
 /**
@@ -87,7 +88,7 @@ class ForwardMessage @JvmOverloads constructor(
      * 消息列表
      */
     val nodeList: Collection<INode>,
-    val displayStrategy: DisplayStrategy = DisplayStrategy.Default
+    @Transient val displayStrategy: DisplayStrategy = DisplayStrategy.Default
 ) : MessageContent {
     init {
         require(nodeList.isNotEmpty()) {

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

@@ -13,7 +13,6 @@
 
 package net.mamoe.mirai.message.data
 
-import kotlinx.serialization.Serializable
 import net.mamoe.mirai.message.data.PokeMessage.Types
 import net.mamoe.mirai.message.data.VipFace.Companion
 import net.mamoe.mirai.utils.PlannedRemoval
@@ -235,7 +234,6 @@ data class VipFace internal constructor(
  *
  * @see Image 查看图片相关信息
  */
-@Serializable
 sealed class FlashImage : MessageContent, HummerMessage() {
     companion object Key : Message.Key<FlashImage> {
         /**
@@ -290,7 +288,6 @@ inline fun Image.flash(): FlashImage = FlashImage(this)
  * @see FlashImage.invoke
  */
 @PlannedRemoval("1.3.0") // internal
-@Serializable
 @Suppress("DEPRECATION", "DEPRECATION_ERROR")
 @Deprecated(
     "use FlashImage instead",
@@ -329,7 +326,6 @@ constructor(override val image: Image) : FlashImage() {
  * @see FlashImage.invoke
  */
 @PlannedRemoval("1.3.0") // internal
-@Serializable
 @Suppress("DEPRECATION", "DEPRECATION_ERROR")
 @Deprecated(
     "use FlashImage instead",