IR: Fix missing source in IrClass with DeepCopyIrTreeWithSymbols

When using DeepCopyIrTreeWithSymbols as class transformer to transform
the IrClass, the source element of IrClass was set to
SourceElement.NO_SOURCE after the transform.

^KT-65343 Fixed

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyIrTreeWithSymbols.kt

@@ -163,6 +163,7 @@ open class DeepCopyIrTreeWithSymbols(
             isExpect = declaration.isExpect,
             isFun = declaration.isFun,
             hasEnumEntries = declaration.hasEnumEntries,
+            source = declaration.source,
         ).apply {
             transformAnnotations(declaration)
             copyTypeParametersFrom(declaration)