Add support to change memory resource used for default data allocator

[grospelliergilles]

The default is to use UnifiedMemory if an accelerator runtime is loaded and Host if it is not the case.
On accelerators where device memory is accessible from host and device (i.e. MI250X, MI300A or GH200), it may be better to use Device as the default memory resource.

[codecov]

Codecov Report

Attention: Patch coverage is 72.41379% with 8 lines in your changes missing coverage. Please review.

Project coverage is 70.26%. Comparing base (1bbc84c) to head (cd9d676).
Report is 6 commits behind head on main.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
arcane/src/arcane/impl/ArcaneMain.cc	0.00%	6 Missing ⚠️
arcane/src/arcane/utils/MemoryUtils.cc	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1808   +/-   ##
=======================================
  Coverage   70.26%   70.26%           
=======================================
  Files        2261     2261           
  Lines      162449   162477   +28     
  Branches    18706    18710    +4     
=======================================
+ Hits       114140   114165   +25     
- Misses      41535    41538    +3     
  Partials     6774     6774           

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