RFR(XS): move FilterClassLoader and ParentLastURLClassLoader to top level testlibrary

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev//8180395/webrev.00/index.html
> 200 lines changed: 101 ins; 99 del; 0 mod;

Hi all,

could you please review this small fix which move FilterClassLoader and ParentLastURLClassLoader class from jdk testlibrary to top level testlibrary?
this fix is a part of ongoing effort on merging and cleaning up our test libraries[1].

webrev: http://cr.openjdk.java.net/~iignatyev//8180395/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8180395

[1]  https://bugs.openjdk.java.net/browse/JDK-8075327

Thanks,
-- Igor