add support for showing configure/build/install options

[boegel]

We should look into supporting some kind of way to figure out how EasyBuild will configure a build (and maybe also how it will execute a build/install, etc.), without actually running it.

This does require unpacking the sources and other steps before, since these steps may determine the configure/build/install options...

Maybe something like eb --show-configure-step, etc.?

[pforai]

👍 on this. Was sought after at JSC hackathon. Also like the idea since I don't have to check the block source for which my desktop/personal config has the appropriate setup but my automated build user that we use to install stuff on real systems doesn't have a nice IDE that can jump conveniently between source locations etc.