Add MLX op handler for aten.isnan #2489

Job	Run time
test-vulkan / test-backend-linux (vulkan, operators) / linux-job	20m 38s
test-vulkan / test-backend-linux (vulkan, models) / linux-job	20m 50s
test-vulkan / test-backend-macos	0s
test-vulkan / package-golden-artifacts	3m 42s
	45m 10s

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