FIR: introduce symbolProvider.getNestedClassifierScope to choose lazy/non-lazy

For some reason this breaks two old FE based tests with member type aliases.
It's not very interesting because member aliases aren't supported.

idea/idea-analysis/src/org/jetbrains/kotlin/idea/fir/IdeFirProvider.kt

@@ -141,6 +141,11 @@ class IdeFirProvider(
         }
     }
 
+    override fun getNestedClassifierScope(classId: ClassId): FirScope? {
+        getFirClassifierByFqName(classId)
+        return cacheProvider.getNestedClassifierScope(classId)
+    }
+
     override fun getClassUseSiteMemberScope(classId: ClassId, useSiteSession: FirSession, scopeSession: ScopeSession): FirScope? {
         getFirClassifierByFqName(classId)
         return cacheProvider.getClassUseSiteMemberScope(classId, useSiteSession, scopeSession)