Add KClass.isFun modifier to reflection

#KT-38881 Fixed

compiler/testData/codegen/box/reflection/modifiers/classes.kt

@@ -1,8 +1,7 @@
-// IGNORE_BACKEND: JS_IR
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS, NATIVE
-
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
 // WITH_REFLECT
+// FILE: box.kt
 
 import kotlin.test.assertTrue
 import kotlin.test.assertFalse
@@ -12,6 +11,7 @@ sealed class S {
     inner class InnerClass
     companion object
     object NonCompanionObject
+    fun interface FunInterface { fun invoke() }
 }
 
 fun box(): String {
@@ -22,26 +22,49 @@ fun box(): String {
     assertFalse(S::class.isData)
     assertFalse(S::class.isInner)
     assertFalse(S::class.isCompanion)
+    assertFalse(S::class.isFun)
 
     assertFalse(S.DataClass::class.isSealed)
     assertTrue(S.DataClass::class.isData)
     assertFalse(S.DataClass::class.isInner)
     assertFalse(S.DataClass::class.isCompanion)
+    assertFalse(S.DataClass::class.isFun)
 
     assertFalse(S.InnerClass::class.isSealed)
     assertFalse(S.InnerClass::class.isData)
     assertTrue(S.InnerClass::class.isInner)
     assertFalse(S.InnerClass::class.isCompanion)
+    assertFalse(S.InnerClass::class.isFun)
 
     assertFalse(S.Companion::class.isSealed)
     assertFalse(S.Companion::class.isData)
     assertFalse(S.Companion::class.isInner)
     assertTrue(S.Companion::class.isCompanion)
+    assertFalse(S.Companion::class.isFun)
 
     assertFalse(S.NonCompanionObject::class.isSealed)
     assertFalse(S.NonCompanionObject::class.isData)
     assertFalse(S.NonCompanionObject::class.isInner)
     assertFalse(S.NonCompanionObject::class.isCompanion)
+    assertFalse(S.NonCompanionObject::class.isFun)
+
+    assertFalse(S.FunInterface::class.isSealed)
+    assertFalse(S.FunInterface::class.isData)
+    assertFalse(S.FunInterface::class.isInner)
+    assertFalse(S.FunInterface::class.isCompanion)
+    assertTrue(S.FunInterface::class.isFun)
+
+    assertFalse(JavaInterface::class.isSealed)
+    assertFalse(JavaInterface::class.isData)
+    assertFalse(JavaInterface::class.isInner)
+    assertFalse(JavaInterface::class.isCompanion)
+    assertFalse(JavaInterface::class.isFun)
 
     return "OK"
 }
+
+// FILE: JavaInterface.java
+
+public interface JavaInterface {
+    int invoke(String s);
+}