xyst

Port over latest AMR from quinoa::develop

This commit ports over about 6-9 months of progress on AMR. Thanks
to @apandare AMR is now nearing completion.

This port is based on quinoa@e2b0d94ab (Mon Sep 19 15:03:36 2022).

All regression tests pass (including the newly added AMR Sod one) but
two fail in SMP mode (also in Quinoa):

  171 - inciter:amr_t0ref_ii_pe2_ppn2 (Failed)
  172 - inciter:amr_t0ref_iu_trans_pe2_ppn2 (Failed)