jvm-abi-gen: consider private type aliases to be public API

They can be referenced from public declarations right now.

^KT-54500 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/serialization/JvmSerializerExtension.kt

@@ -73,7 +73,8 @@ class JvmSerializerExtension @JvmOverloads constructor(
     }
 
     override fun shouldSerializeTypeAlias(descriptor: TypeAliasDescriptor): Boolean {
-        return classBuilderMode != ClassBuilderMode.ABI || descriptor.visibility != DescriptorVisibilities.PRIVATE
+        // TODO: do not serialize private type aliases in ABI class builder mode once KT-17229 is fixed.
+        return true
     }
 
     override fun shouldSerializeNestedClass(descriptor: ClassDescriptor): Boolean {