LC: commonize facade for multi-file class

analysis/light-classes-base/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForFacade.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.psi.KtFile
 interface KtLightClassForFacade : KtLightClass {
     val facadeClassFqName: FqName
     val files: Collection<KtFile>
+    val multiFileClass: Boolean
 
     override fun getName(): String = facadeClassFqName.shortName().asString()
 }

analysis/light-classes-base/src/org/jetbrains/kotlin/asJava/classes/KtLightClassForFacadeBase.kt

@@ -35,12 +35,12 @@ abstract class KtLightClassForFacadeBase constructor(
 ) : KtLightClassBase(files.first().manager), KtLightClassForFacade {
     private val firstFileInFacade by lazyPub { files.first() }
 
-    val isMultiFileClass: Boolean by lazyPub {
+    override val multiFileClass: Boolean by lazyPub {
         files.size > 1 || firstFileInFacade.isJvmMultifileClassFile
     }
 
     private val _modifierList: PsiModifierList by lazyPub {
-        if (isMultiFileClass)
+        if (multiFileClass)
             LightModifierList(manager, KotlinLanguage.INSTANCE, PsiModifier.PUBLIC, PsiModifier.FINAL)
         else
             createModifierListForSimpleFacade()