Enrollment Check For Private Key Encryption

[andrewpmartinez]

When enrolling if a private key is supplied that has password protection, it is blindly used and the user receives an ANS1 error.

Example Where test.key is password protected:

ziti-tunnel enroll -j test.jwt -o test.json -k test.key -c test.pem
ERROR   error: failed to enroll: asn1: structure error: length too large