Add HOHQMesh reader

[jlchan]

Adds capability to read HOHQMesh .mesh files (see https://trixi-framework.github.io/HOHQMesh/TheISMMeshFileFormats/).

Also adds capability to read (unreleased) triangular .mesh files. Tetrahedral meshes are not yet supported.

[codecov[bot]]

Codecov Report

Merging #91 (adc5565) into main (fc50ed7) will increase coverage by 0.30%. The diff coverage is 97.89%.

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
+ Coverage   96.82%   97.13%   +0.30%     
==========================================
  Files          22       24       +2     
  Lines        2491     2649     +158     
==========================================
+ Hits         2412     2573     +161     
+ Misses         79       76       -3     

Impacted Files	Coverage Δ
src/StartUpDG.jl	100.00% <ø> (ø)
src/mesh/simple_meshes.jl	99.38% <ø> (+1.75%)	:arrow_up:
src/mesh/gmsh_utilities.jl	96.00% <96.00%> (ø)
src/mesh/hohqmesh_utilities.jl	100.00% <100.00%> (ø)

... and 2 files with indirect coverage changes

:mega: We’re building smart automated test selection to slash your CI/CD build times. Learn more