Multiphysics (production)

[majosm]

Working-ish draft of grudge-based multiphysics. Need to separate some of this out into simpler PRs.

Depends on inducer/grudge#246, inducer/meshmode#309.

Questions for the review:

• Is the scope and purpose of the PR clear?
  • The PR should have a description.
  • The PR should have a guide if needed (e.g., an ordering).
• Is every top-level method and class documented? Are things that should be documented actually so?
• Is the interface understandable? (I.e. can someone figure out what stuff does?) Is it well-defined?
• Does the implementation do what the docstring claims?
• Is everything that is implemented covered by tests?
• Do you see any immediate risks or performance disadvantages with the design? Example: what do interface normals attach to?

[majosm]

Superseded by #726 and #767.