O3DE/o3de-extras @ multi-device-resource-fixes

kberg-amzn 2ce44c0843 Initial attempt at multithreaded training, still requires cleanup, plus numerous other changes and fixes. ImGui driven backprop is not converging correctly, requires more debugging.		2 lat temu
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LayerTests.cpp	2ce44c0843 Initial attempt at multithreaded training, still requires cleanup, plus numerous other changes and fixes. ImGui driven backprop is not converging correctly, requires more debugging.	2 lat temu
MultilayerPerceptronTests.cpp	2ce44c0843 Initial attempt at multithreaded training, still requires cleanup, plus numerous other changes and fixes. ImGui driven backprop is not converging correctly, requires more debugging.	2 lat temu