How to run jit-diffs for changes in the managed code

All commands are in powershell, should be pretty much the same for bash and non-windows platforms

1. build everything we're going to need:

.\build.cmd Clr+Libs -c Release ;; .\build.cmd Clr -c Checked ;; cd .\src\tests\ ;; .\build.cmd Release generatelayoutonly ;; cd ..\..

2. Make a copy of the test core_root (will be a baseline):