FIR: Add FirTypeScope

^KT-35495 Relates

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirScopeProvider.kt

@@ -14,7 +14,7 @@ abstract class FirScopeProvider {
         klass: FirClass<*>,
         useSiteSession: FirSession,
         scopeSession: ScopeSession
-    ): FirScope
+    ): FirTypeScope
 
     abstract fun getStaticMemberScopeForCallables(
         klass: FirClass<*>,

compiler/fir/tree/src/org/jetbrains/kotlin/fir/scopes/FirTypeScope.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2020 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.fir.scopes
+
+import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
+
+abstract class FirTypeScope : FirScope() {
+    // Initially, this method is intended to belong only to this class, but not to FirScope
+    // But the main-use case (FirSyntheticPropertiesScope) uses it on arbitrary type (intersection and others) that currently use
+    // scope implementations for type-unrelated scopes as well
+    // One of the idea how to fix it is considered extracting it to the interface
+    //
+    // The idea behind this class and abstract override is to explicitly state that those implementations should implement this method properly
+    // and use other FirOverrideAwareScope when delegating to them (as in FirClassSubstitutionScope)
+    abstract override fun processOverriddenFunctions(
+        functionSymbol: FirFunctionSymbol<*>,
+        processor: (FirFunctionSymbol<*>) -> ProcessorAction
+    ): ProcessorAction
+}