Add KmFlexibleTypeUpperBound.Companion and JVM_PLATFORM_TYPE_ID extension on it.

Because `public JvmTypeExtensionVisitor` was removed, a new place for `const val PLATFORM_TYPE_ID`
is required. It is logical to place it as a some kind of constant for Km node;
however, because it is platform-specific, there is a need for an empty
`KmFlexibleTypeUpperBound.Companion` in metadata common sources
and `public val KmFlexibleTypeUpperBound.Companion.PLATFORM_TYPE_ID`
extension in kotlin-metadata-jvm sources.

See also: KT-63156

libraries/kotlinx-metadata/jvm/api/kotlin-metadata-jvm.api

@@ -483,6 +483,7 @@ public final class kotlin/metadata/KmEffectType : java/lang/Enum {
 }
 
 public final class kotlin/metadata/KmFlexibleTypeUpperBound {
+	public static final field Companion Lkotlin/metadata/KmFlexibleTypeUpperBound$Companion;
 	public fun <init> (Lkotlin/metadata/KmType;Ljava/lang/String;)V
 	public final fun component1 ()Lkotlin/metadata/KmType;
 	public final fun component2 ()Ljava/lang/String;
@@ -497,6 +498,9 @@ public final class kotlin/metadata/KmFlexibleTypeUpperBound {
 	public fun toString ()Ljava/lang/String;
 }
 
+public final class kotlin/metadata/KmFlexibleTypeUpperBound$Companion {
+}
+
 public final class kotlin/metadata/KmFunction {
 	public field returnType Lkotlin/metadata/KmType;
 	public fun <init> (Ljava/lang/String;)V
@@ -730,6 +734,7 @@ public final class kotlin/metadata/jvm/JvmExtensionsKt {
 	public static final fun getAnonymousObjectOriginName (Lkotlin/metadata/KmClass;)Ljava/lang/String;
 	public static final fun getFieldSignature (Lkotlin/metadata/KmProperty;)Lkotlin/metadata/jvm/JvmFieldSignature;
 	public static final fun getGetterSignature (Lkotlin/metadata/KmProperty;)Lkotlin/metadata/jvm/JvmMethodSignature;
+	public static final fun getJVM_PLATFORM_TYPE_ID (Lkotlin/metadata/KmFlexibleTypeUpperBound$Companion;)Ljava/lang/String;
 	public static final fun getLambdaClassOriginName (Lkotlin/metadata/KmFunction;)Ljava/lang/String;
 	public static final fun getLocalDelegatedProperties (Lkotlin/metadata/KmClass;)Ljava/util/List;
 	public static final fun getLocalDelegatedProperties (Lkotlin/metadata/KmPackage;)Ljava/util/List;

libraries/kotlinx-metadata/jvm/src/kotlin/metadata/jvm/JvmExtensions.kt

@@ -8,6 +8,7 @@
 
 package kotlin.metadata.jvm
 
+import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmProtoBufUtil
 import kotlin.metadata.*
 import kotlin.metadata.jvm.internal.jvm
 
@@ -172,3 +173,11 @@ public var KmType.isRaw: Boolean
  */
 public val KmType.annotations: MutableList<KmAnnotation>
     get() = jvm.annotations
+
+
+/**
+ * The type flexibility id, signifying that the visited type is a JVM platform type.
+ *
+ * @see KmFlexibleTypeUpperBound.typeFlexibilityId
+ */
+public val KmFlexibleTypeUpperBound.Companion.JVM_PLATFORM_TYPE_ID: String get() = JvmProtoBufUtil.PLATFORM_TYPE_ID

libraries/kotlinx-metadata/jvm/src/kotlin/metadata/jvm/internal/JvmExtensionNodes.kt

@@ -121,12 +121,5 @@ internal class JvmTypeExtension : KmTypeExtension {
     companion object {
         @JvmField
         val TYPE: KmExtensionType = KmExtensionType(JvmTypeExtension::class)
-
-        /**
-         * The type flexibility id, signifying that the visited type is a JVM platform type.
-         *
-         * @see KmTypeVisitor.visitFlexibleTypeUpperBound
-         */
-        const val PLATFORM_TYPE_ID: String = JvmProtoBufUtil.PLATFORM_TYPE_ID // TODO: move out of deprecated visitor
     }
 }

libraries/kotlinx-metadata/src/kotlin/metadata/Nodes.kt

@@ -588,7 +588,12 @@ public data class KmTypeProjection(var variance: KmVariance?, var type: KmType?)
  * @property typeFlexibilityId id of the kind of flexibility this type has. For example, "kotlin.jvm.PlatformType" for JVM platform types,
  *                          or "kotlin.DynamicType" for JS dynamic type
  */
-public data class KmFlexibleTypeUpperBound(var type: KmType, var typeFlexibilityId: String?)
+public data class KmFlexibleTypeUpperBound(var type: KmType, var typeFlexibilityId: String?) {
+    /**
+     * A companion object providing possibility to declare various platform-dependent constant ids as extension properties of it.
+     */
+    public companion object
+}
 
 /**
  * Variance applied to a type parameter on the declaration site (*declaration-site variance*),

libraries/tools/kotlinp/jvm/src/org/jetbrains/kotlin/kotlinp/jvm/JvmKotlinp.kt

@@ -193,8 +193,7 @@ class JvmKotlinp(settings: Settings) : Kotlinp(settings) {
     override fun isRaw(type: KmType) = type.isRaw
 
     override fun renderFlexibleTypeUpperBound(flexibleTypeUpperBound: KmFlexibleTypeUpperBound): String? {
-        @Suppress("DEPRECATION_ERROR")
+        return if (flexibleTypeUpperBound.typeFlexibilityId == KmFlexibleTypeUpperBound.JVM_PLATFORM_TYPE_ID)
-        return if (flexibleTypeUpperBound.typeFlexibilityId == JvmTypeExtensionVisitor.PLATFORM_TYPE_ID)
             printString { appendType(flexibleTypeUpperBound.type) }
         else
             null