MLX delegate: add integer support for aten.bitwise_not #3276

Job	Run time
test-coreml / test-backend-macos (coreml, operators) / macos-job	16m 56s
test-coreml / test-backend-macos (coreml, models) / macos-job	19m 2s
test-coreml / package-golden-artifacts	0s
test-coreml / test-backend-linux	-9s
	35m 49s

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