Refactor usage of accelerator API for constituents and add documentation

[grospelliergilles]

• Use template classes for common commands on materials and environments
• Add explicit classes for iterator values
• Add documentation

[codecov]

Codecov Report

Attention: Patch coverage is 96.05263% with 3 lines in your changes missing coverage. Please review.

Project coverage is 70.28%. Comparing base (0c1e453) to head (a185294).
Report is 5 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...c/arcane/accelerator/RunCommandMaterialEnumerate.h	94.73%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1875      +/-   ##
==========================================
- Coverage   70.29%   70.28%   -0.01%     
==========================================
  Files        2275     2275              
  Lines      163780   163762      -18     
  Branches    18863    18863              
==========================================
- Hits       115124   115102      -22     
- Misses      41829    41831       +2     
- Partials     6827     6829       +2     

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