Get rid of SGX_MODE for SecretCLI

[Cashmaney]

Having to set SGX_MODE=SW and having it affect anything for secretcli is stupid. The only reason it's there is to know how to parse the certificates that contain the enclave's public keys.

We should either:

A. Just try to parse the certificate as production (SGX_MODE=HW), if that fails try to parse it as dev (SGX_MODE=SW), and only after that fails return B. Add a config option to toggle between dev/prod/both

Also the error message returning from CLI should be changed to make more sense for the user