javac-wrapper: refactoring, fixes and tests

compiler/testData/javac/diagnostics/tests/inheritance/InheritedInnerUsageInInner.kt

@@ -0,0 +1,31 @@
+// FILE: a/x.java
+package a;
+
+public class x {
+
+    public class z {}
+
+}
+
+// FILE: a/y.java
+package a;
+
+public class y extends x {
+
+    public z getZ() { return null; }
+
+    public class d {
+
+        public z getZ() { return null; }
+
+    }
+
+}
+
+// FILE: test.kt
+package test
+
+import a.y
+
+fun test() = y().getZ()
+fun test2() = y().d().getZ()