Add blindsigning in Settings for nano. #1084

Job	Run time
Build application (nanos)	1m 41s
Build application (nanosp)	1m 41s
Build application (nanox)	1m 48s
Build application (stax)	1m 56s
Build application (flex)	1m 50s
build_docker_tezos_ocaml / Build docker image	15s
generate_samples_unit_tests	2m 23s
integration_tests_basic (nanos)	3m 43s
integration_tests_basic (nanosp)	3m 33s
integration_tests_basic (nanox)	3m 35s
integration_tests_basic (stax)	2m 47s
integration_tests_basic (flex)	3m 4s
integration_tests_samples (nanos, micheline)	3m 13s
integration_tests_samples (nanos, operations)	5m 21s
integration_tests_samples (nanosp, micheline)	3m 21s
integration_tests_samples (nanosp, operations)	5m 21s
integration_tests_samples (nanox, micheline)	3m 8s
integration_tests_samples (nanox, operations)	5m 0s
	53m 40s

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