Add support for MultiField on GPU

[sbrdar]

• Add FieldSet functions for device memory management via Field
• Add support for the copy-on-device of discontiguous host memory
• Add support for MultiField on the device

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 66.37931% with 273 lines in your changes are missing coverage. Please review.

Project coverage is 79.78%. Comparing base (3bcbdb8) to head (33083ef). Report is 39 commits behind head on develop.

Files	Patch %	Lines
src/atlas_f/field/atlas_FieldSet_module.fypp	2.56%	152 Missing :warning:
src/atlas/field/detail/FieldInterface.cc	0.00%	21 Missing :warning:
src/atlas/field/detail/MultiFieldInterface.cc	70.83%	21 Missing :warning:
src/tests/field/test_multifield_ifs.cc	90.72%	14 Missing :warning:
src/atlas/util/RegisterPointerInfo.cc	0.00%	11 Missing :warning:
src/atlas_f/field/atlas_MultiField_module.fypp	68.75%	10 Missing :warning:
src/atlas/array/native/NativeDataStore.h	82.00%	9 Missing :warning:
src/atlas/array/native/NativeArray.cc	89.06%	7 Missing :warning:
src/atlas/array/Array.h	0.00%	4 Missing :warning:
src/atlas/array/ArraySpec.cc	69.23%	4 Missing :warning:
... and 9 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #201 +/- ## =========================================== - Coverage 80.07% 79.78% -0.29% =========================================== Files 859 792 -67 Lines 63684 62656 -1028 =========================================== - Hits 50995 49993 -1002 + Misses 12689 12663 -26 ```

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[wdeconinck]

This PR will be split up in different ones.

• first up is #229
• then add GPU support via pluto
• then update remaining features and resolve conflicts.