Introduce MemberScope::classifierNames and some implementations

It aims to help with further optimizations

idea/ide-common/src/org/jetbrains/kotlin/idea/kdoc/resolveKDocLink.kt

@@ -253,6 +253,8 @@ private class ExtensionsScope(
                 .toSet()
     }
 
+    override fun getClassifierNames() = null
+
     override fun printScopeStructure(p: Printer) {
         p.println("Extensions for ${receiverClass.name} in:")
         contextScope.printStructure(p)

idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/IdeSampleResolutionService.kt

@@ -75,8 +75,8 @@ private class GlobalSyntheticPackageViewDescriptor(override val fqName: FqName,
         override fun getContributedFunctions(name: Name, location: LookupLocation): Collection<SimpleFunctionDescriptor> = shouldNotBeCalled()
 
         override fun getFunctionNames(): Set<Name> = shouldNotBeCalled()
-
         override fun getVariableNames(): Set<Name> = shouldNotBeCalled()
+        override fun getClassifierNames(): Set<Name> = shouldNotBeCalled()
 
         override fun getContributedClassifier(name: Name, location: LookupLocation): ClassifierDescriptor? = shouldNotBeCalled()
 
@@ -130,4 +130,4 @@ private class GlobalSyntheticPackageViewDescriptor(override val fqName: FqName,
     override fun acceptVoid(visitor: DeclarationDescriptorVisitor<Void, Void>?) = shouldNotBeCalled()
 
     override val annotations = Annotations.EMPTY
-}
+}