make shock tube and blast wave tests run for SRHD when using MDA AV

The key step was to adapt a 'covariant' regularization that looks like

\partial_t D + \partial_x f_D^x = - \partial_x ( \mu ( \partial_t - \partial_x ) D ),

where the time derivative on the RHS is new compared to previous attempts. We approximate

\partial_t D

by the

- \partial_x f_D^x

.

Note that this is not truely covariant, but

(\partial_t - \partial_x) ( \mu ( \partial_t - \partial_x ) D)

would be. Problem is that we don't know how to approximate the second time derivatives or the mixed time-space derivatives. But it works this way, so leave it for now.

This PR adds example parameter files that allow to reproduce the SRHD tests from https://arxiv.org/pdf/2202.08839.pdf. To run the blastwave2 test it was important to add correct the evolved variable tau whenever the energy density eps turned slightly negative, as suggested in https://arxiv.org/pdf/2005.01821.pdf III.A. What is interesting is that atm we don't need an atmosphere description, but that's probably because those tests do not examine low densities.

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Side note: Realized that !75 (merged) promoted Mesh to a parameteric type and now most of the HRSC and TCI structs suffer from type instabilities. Need to fix this in a separate PR.

added SRHD equation labels

added 27 commits

• 285a652c - 1 commit from branch main
• 285a652c...e98fcefd - 16 earlier commits
• 769f1496 - commit conservative_fixing experiments (not active)
• e30ffc60 - fixup blastwave2 test; don't smooth FVElement mesh initial data
• 9ad17115 - add blastwave2 examples
• 58b1aa3f - add blastwave1 example
• 383f48f0 - determine initial viscosity using all dynamic variables as indicators
• 7ff0ae4a - don't recompute max speed for timestep
• 82fcd84b - adjust tau when energy density exceeds lower bound
• 29139416 - update blastwave1/2 av mda examples
• ee308410 - cons2prim: disable simd; disable atmosphering warning
• f4e06edd - mda: use inplace operations

Compare with previous version

enabled an automatic merge when the pipeline for f4e06edd succeeds

aborted the automatic merge because source branch was updated

added 2 commits

• 02b11157 - fix up dispatch of register_variables; fix up smoothing on initial data
• 41edecdf - update ref test data srhd_simple_wave_avmda

Compare with previous version

enabled an automatic merge when the pipeline for 41edecdf succeeds

merged

mentioned in commit d7d9f647