[FIR] Fix effective visibility handling for local members

In future 'Local' effective visibility could be used
as a flag of local declaration

compiler/fir/analysis-tests/testData/resolve/localClasses/implicitInAnonymous.txt

@@ -1,6 +1,6 @@
 FILE: implicitInAnonymous.kt
     private final val x: R|anonymous| = object : R|kotlin/Any| {
-        private constructor(): R|anonymous| {
+        private[local] constructor(): R|anonymous| {
             super<R|kotlin/Any|>()
         }