[AA] Add KtClass-based KotlinSealedInheritorsProvider

- The compiler's `SealedClassInheritorsProvider` should not be exposed
  outside LL FIR, as it is an internal compiler component and also
  exposes `FirRegularClass`. `KotlinSealedInheritorsProvider` is an
  Analysis API provider for sealed inheritors that accepts a `KtClass`
  instead.

^KT-64718 fixed

analysis/analysis-api-providers/src/org/jetbrains/kotlin/analysis/providers/KotlinSealedInheritorsProvider.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2010-2024 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.analysis.providers
+
+import com.intellij.openapi.project.Project
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.psi.KtClass
+
+/**
+ * [KotlinSealedInheritorsProvider] provides a list of direct inheritors for sealed [KtClass]es (which may be a class or an interface). It
+ * may be created with [KotlinSealedInheritorsProviderFactory].
+ *
+ * Implementations of this service should consider caching the results. The [KotlinSealedInheritorsProvider] is tied to the lifetime of its
+ * owning session, so it will be invalidated automatically with the session.
+ */
+public interface KotlinSealedInheritorsProvider {
+    /**
+     * Returns the sealed inheritors of [ktClass], which may be a class or an interface. [ktClass] is guaranteed to be sealed.
+     */
+    public fun getSealedInheritors(ktClass: KtClass): List<ClassId>
+}
+
+public interface KotlinSealedInheritorsProviderFactory {
+    /**
+     * Creates a [KotlinSealedInheritorsProvider] for a session.
+     */
+    public fun createSealedInheritorsProvider(): KotlinSealedInheritorsProvider
+
+    public companion object {
+        public fun getInstance(project: Project): KotlinSealedInheritorsProviderFactory? =
+            project.getService(KotlinSealedInheritorsProviderFactory::class.java)
+    }
+}