[TEST] Migrate duplicating javac tests to new test runners

Also minimize scope of DiagnosticUsingJavac tests to
 `compiler/testData/diagnostics/tests/javac`. This is fine since
 javac compilation mode is still not finished and no one not going to
 support it

compiler/testData/diagnostics/tests/javac/imports/PackagePrivateAndPublicNested.fir.kt

@@ -0,0 +1,19 @@
+// FILE: p/Foo.java
+package p;
+
+class Foo {
+    public static class Nested {}
+}
+
+// FILE: foo.kt
+package a
+
+import p.Foo
+import p.Foo.Nested
+
+class Bar : <!EXPOSED_SUPER_CLASS, HIDDEN!>Foo<!>() {
+    protected fun <!EXPOSED_FUNCTION_RETURN_TYPE!>foo<!>(): Nested? = null
+}
+
+private fun foo(): Nested? = null
+private fun bar(): p.Foo.Nested? = null