Canonicalize CoseKey CBOR serialization. #72

Job	Run time
build_attest_all (buildconfigs/key_xor_test_app.sh)	2m 11s
build_attest_all (buildconfigs/oak_containers_kernel.sh)	24m 15s
build_attest_all (buildconfigs/oak_containers_orchestrator.sh)	6m 15s
build_attest_all (buildconfigs/oak_containers_stage1.sh)	3m 47s
build_attest_all (buildconfigs/oak_containers_syslogd.sh)	5m 50s
build_attest_all (buildconfigs/oak_containers_system_image.sh)	12m 49s
build_attest_all (buildconfigs/oak_echo_enclave_app.sh)	2m 10s
build_attest_all (buildconfigs/oak_echo_raw_enclave_app.sh)	2m 19s
build_attest_all (buildconfigs/oak_functions_enclave_app.sh)	2m 39s
build_attest_all (buildconfigs/oak_functions_insecure_enclave_app.sh)	2m 32s
build_attest_all (buildconfigs/oak_orchestrator.sh)	2m 21s
build_attest_all (buildconfigs/oak_restricted_kernel_simple_io_init_rd_wrapper_bin.sh)	2m 38s
build_attest_all (buildconfigs/stage0_bin.sh)	2m 42s
	1h 12m 28s

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