[platform-ui-dev] New ui test plugins

[Tod Creasey <Tod_Creasey@xxxxxxxxxx>]

As of today we have moved to using 3 plug-ins for our tests. The tests 
themselves have not changed, they have only been refactored.

org.eclipse.ui.tests.harness for code that is common between our test 
plug-ins (it is a prerequisite of the other two)
org.eclipse.ui.tests (the old one) for our non-performance test suites 
org.eclipse.ui.tests.performance for the performance suites

Sonia and I have also updated the build configuration to use the new 
suites. Please load org.eclipse.ui.tests.harness should you want to run 
tests from the other two.

Tod