Prepare and pursue Chapel's application to E4S

[bonachea]

Now that Chapel finally has a high-quality Spack package, the next logical step is to pursue Chapel membership in the E4S Programming Model SDK.

E4S is a DOE ASCR product that provides pre-built container images with selected Spack packages for a variety of systems, and (perhaps more importantly) professionally managed deployments on DOE production HPC centers. Getting Chapel into E4S is a relatively low-effort approach to have it incorporated into the modules installed across a large set of important systems.

You can read about the E4S membership criteria here. Off-hand I suspect that Chapel already roughly meets many of the required criteria, but a few (notably including P2 and P5) will probably require some minor additional effort. It's worth noting that many of these criteria come down to a judgement call. As such, I suggest it's in Chapel's best interest to ensure we're prepared to make a strong and coordinated case for how Chapel fulfills each of the required criteria, before proceeding with an application for E4S membership.

I'd like to be involved in this process.