[FIR generator] Move Implementation.Kind to common module

This is a step towards commonizing the code generator between
FIR and IR: KT-61970

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/ImplementationKind.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.generators.tree
+
+enum class ImplementationKind(val title: String, val typeKind: TypeKind) {
+    Interface("interface", TypeKind.Interface),
+    FinalClass("class", TypeKind.Class),
+    OpenClass("open class", TypeKind.Class),
+    AbstractClass("abstract class", TypeKind.Class),
+    SealedClass("sealed class", TypeKind.Class),
+    SealedInterface("sealed interface", TypeKind.Interface),
+    Object("object", TypeKind.Class);
+
+    val isInterface: Boolean
+        get() = typeKind == TypeKind.Interface
+}

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/ImplementationKindOwner.kt

@@ -0,0 +1,11 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.generators.tree
+
+interface ImplementationKindOwner : Importable {
+    var kind: ImplementationKind?
+    val allParents: List<ImplementationKindOwner>
+}

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/TypeKind.kt

@@ -0,0 +1,10 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.generators.tree
+
+enum class TypeKind {
+    Class, Interface
+}