Eclipse does not have the ability to differentiate test dependencies
from main dependencies. This causes what looks like a circular
dependency through test-framework. This change sets up an additional
core-tests project for eclipse only, which removes this problem.
The RR gradle plugin is at
https://github.com/randomizedtesting/gradle-randomized-testing-plugin.
However, we currently have a copy of this, since the plugin is still in
heavy development. This change moves the files around so they can be
copied directly from the elasticsearch fork to that repo, for ease of
syncing.
The test jar was previously built in maven by copying class files. With
gradle we now have a proper test framework artifact. This change moves
the classes used by the test framework into the test-framework module.
See #13930