Modernize Mirgecom

[thomasgibson]

This PR does the following:

1. Removes the use of grudge.discretization.EagerDiscretization. Why? Because grudge is, for the most part, agnostic to whether arrays are eager, gpu, or lazy. It is the job of arraycontext to sort out the behavior of arrays, not grudge. Moreover, this uses the more stable (non-deprecated) interface of grudge.
2. Updates deprecated imports from meshmode to the new arraycontext package. This also includes the swapping of arguments for functions like thaw.
3. Renames wave-eager-x.py -> wave-x.py. This is because of item 1. When lazy evaluation comes in, the only thing that should really change (from mirgecom's perspective) is the use of a new lazy array context. Apparently CI didn't like this.

[thomasgibson]

So my plan is to wait until inducer/grudge#74 is merged before this PR is "ready." However, I think we should keep commenting about the user interface until we're all happy with it.

[inducer]

Thanks @thomasgibson for taking this on! (Just did a quick scroll here, no huge red flags spotted.)

[inducer]

Unsubscribing... @-mention or request review once it's ready for a look or needs attention.

[thomasgibson]

Haven't forgotten about this PR; I would prefer to have inducer/grudge#122 in first

[MTCam]

Haven't forgotten about this PR; I would prefer to have inducer/grudge#122 in first

Hey @thomasgibson , I think this addresses some portion of #509 ?

[thomasgibson]

Haven't forgotten about this PR; I would prefer to have inducer/grudge#122 in first

Hey @thomasgibson , I think this addresses some portion of #509 ?

Yes it indeed does! It will take care of removing references to discr (and allow us to remove EagerDGDiscretization all together)