Unify write() method and make it a member of KotlinClassMetadata

To make sure that the correct version and flags are preserved during metadata transformation,
they are now stored inside KotlinClassMetadata.
Such change also makes it possible to make write() a member function of KotlinClassMetadata, further simplifying API.
Also, it allows tracking whether readStrict or readLenient was used to read metadata and prohibit writing accordingly.

Also provide transform() method as a shortcut for readStrict+write.

Related to: #KT-59441

plugins/jvm-abi-gen/src/org/jetbrains/kotlin/jvm/abi/JvmAbiMetadataProcessor.kt

@@ -28,28 +28,19 @@ fun abiMetadataProcessor(annotationVisitor: AnnotationVisitor): AnnotationVisito
         } ?: intArrayOf(1, 4)
 
         val newHeader = runCatching {
-            when (val metadata = KotlinClassMetadata.readStrict(header)) {
-                is KotlinClassMetadata.Class -> {
-                    val klass = metadata.kmClass
-                    klass.removePrivateDeclarations()
-                    KotlinClassMetadata.writeClass(klass, metadataVersion, header.extraInt)
+            KotlinClassMetadata.transform(header) { metadata ->
+                when (metadata) {
+                    is KotlinClassMetadata.Class -> {
+                        metadata.kmClass.removePrivateDeclarations()
+                    }
+                    is KotlinClassMetadata.FileFacade -> {
+                        metadata.kmPackage.removePrivateDeclarations()
+                    }
+                    is KotlinClassMetadata.MultiFileClassPart -> {
+                        metadata.kmPackage.removePrivateDeclarations()
+                    }
+                    else -> Unit
                 }
-                is KotlinClassMetadata.FileFacade -> {
-                    val pkg = metadata.kmPackage
-                    pkg.removePrivateDeclarations()
-                    KotlinClassMetadata.writeFileFacade(pkg, metadataVersion, header.extraInt)
-                }
-                is KotlinClassMetadata.MultiFileClassPart -> {
-                    val pkg = metadata.kmPackage
-                    pkg.removePrivateDeclarations()
-                    KotlinClassMetadata.writeMultiFileClassPart(
-                        pkg,
-                        metadata.facadeClassName,
-                        metadataVersion,
-                        header.extraInt
-                    )
-                }
-                else -> header
             }
         }.getOrElse { cause ->
             // TODO: maybe jvm-abi-gen should throw this exception by default, and not only in tests.