💻 Add a repartition flag to resume using manual h4 files

[kks32]

Describe the PR
When using a manually written particles HDF5 files and resuming from step 0, it will typically call mesh_->resume_domain_cell_ranks() which then assigns the current MPI_RANK to the cell if the cell has particles in it. This works on the assumption that the current cell has particles only on the current rank - which is true when generated using our MPM code, but not for particles generated manually and written to HDF5 file. When particles are distributed across different MPI ranks for the same cell, MPI_Reduce will result in MPI_RANK larger than the MPI_SIZE (bad!) - assigning to a different MPI rank as long as it's within MPI_SIZE is bad for efficiency, which will be resolved in the subsequent step.

This PR adds a boolean flag called repartition: true to resume JSON to enable repartitioning when resuming from a HDF5 file. This is an optional flag which is set to false.

Additional context
Input file change:

"analysis": {
		"resume": {
			"resume": true,
			"repartition": true,
			"uuid": "slope",
			"step": 0
		}
}

[codecov]

Codecov Report

Merging #721 (2531ed9) into develop (087bd86) will decrease coverage by 0.02%.
The diff coverage is 66.67%.

@@             Coverage Diff             @@
##           develop     #721      +/-   ##
===========================================
- Coverage    96.77%   96.75%   -0.02%     
===========================================
  Files          130      130              
  Lines        25920    25932      +12     
===========================================
+ Hits         25083    25090       +7     
- Misses         837      842       +5     

Impacted Files	Coverage Δ
include/mesh.tcc	82.77% <50.00%> (-0.22%)	⬇️
include/solvers/mpm_explicit.tcc	93.24% <77.78%> (-2.34%)	⬇️

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[jgiven100]

bool flag seems like a simple (and non-breaking) fix for this