Reporting loaded modules/current manifest

[staticfloat]

It might be very helpful to include in the upload a Manifest showing all the artifacts/packages reachable by the code that ran. While detecting activate() invocations in arbitrary julia code that might crash may not be easy, we can probably rely on most users that are using --bug-report=rr to also provide a --project if they're submitting something nicely-formed, so we can just snarf that at InteractiveUtils.report_bug() time, before we pass it off to the child Julia process.

[Keno]

The artifact will have been read by Julia, so it's included in the trace. My plan is to have a post-processing step that does some common analysis and prepares a template for you that prints things like the Projects/Manifest, versioninfo, etc.