genbotcert command

Command genbotcert can both generate a CSR and private key for a LUCI bot and generate a certificate from a CSR. It accepts two arguments, the bot hostname, and the path to the CSR. If it only receives the hostname then it writes the PEM-encoded CSR to the current working directory along with a private key. If it receives both the hostname and CSR path then it validates that the hostname is what is what is expected in the CSR and generates a certificate. The certificate is written to the current working directory.