Allow Harness to Compile Against Non-Friend Modules

Currently module developers who are using the Harness can face with the issue that if they are developing against a non-stable API require friendship, then the Harness build fail. It is quite discouraging.

By introducing a project property like: "netbeans.friendly.modules=true" this build fail could be reduced to warn level. Also the build fail message shall include the availability of this property.