visibility inspection: prefer extension visibility to default one (IDEA-166543)

java/java-tests/testData/inspection/visibility/entryPointWithPredefinedVisibility/expected.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>ThisClass.java</file>
+    <line>2</line>
+    <description>Can be package-private</description>
+  </problem>
+</problems>

java/java-tests/testData/inspection/visibility/entryPointWithPredefinedVisibility/src/ThisClass.java

@@ -0,0 +1,6 @@
+public class ThisClass {
+    public void foo() {}
+    public void bar() {}
+
+    public static void main(String[] args) {}
+}