[IR] Deprecate to use fqName in IrPackageFragment

compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrPackageFragment.kt

@@ -26,4 +26,15 @@ abstract class IrPackageFragment : IrElementBase(), IrDeclarationContainer, IrSy
     abstract val packageFragmentDescriptor: PackageFragmentDescriptor
 
     abstract var packageFqName: FqName
+
+    @Deprecated(
+        message = "Please use `packageFqName` instead",
+        replaceWith = ReplaceWith("packageFqName"),
+        level = DeprecationLevel.ERROR,
+    )
+    var fqName: FqName
+        get() = packageFqName
+        set(value) {
+            packageFqName = value
+        }
 }

compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt

@@ -536,6 +536,18 @@ object IrTree : AbstractTreeBuilder() {
         +symbol(packageFragmentSymbolType)
         +field("packageFragmentDescriptor", type(Packages.descriptors, "PackageFragmentDescriptor"), mutable = false)
         +field("packageFqName", type<FqName>())
+        +field("fqName", type<FqName>()) {
+            baseGetter = code("packageFqName")
+            generationCallback = {
+                val deprecatedAnnotation = AnnotationSpec.builder(Deprecated::class)
+                    .addMember(code("message = \"Please use `packageFqName` instead\""))
+                    .addMember(code("replaceWith = ReplaceWith(\"packageFqName\")"))
+                    .addMember(code("level = DeprecationLevel.ERROR"))
+                    .build()
+                addAnnotation(deprecatedAnnotation)
+                setter(FunSpec.setterBuilder().addParameter("value", FqName::class).addCode(code("packageFqName = value")).build())
+            }
+        }
     }
     val externalPackageFragment: ElementConfig by element(Declaration) {
         visitorParent = packageFragment