jvm-abi-gen: Remove effectively private classes from ABI

#KT-64590 Fixed

plugins/jvm-abi-gen/testData/compare/privateOuterClassForEffectivelyVisibleInterface/sameAbi/test.kt

@@ -0,0 +1,11 @@
+package test
+
+class Outer {
+    class Public : NestedClass.I
+
+    private class NestedClass {
+        interface I
+
+        fun someFun() = Unit
+    }
+}