[RFE] Add set-hostname flag to Azure-init CLI

[cadejacobson]

Current situation

Azure-init is aiming to improve its modularity by adding flags for each feature. We would like to be able to set the hostname using one of these flags.

Ideal future situation

We are able to call one of the below flags to have azure-init pull IMDS data, get the hostname, and write it to an available backend.

Implementation options

• azure-init --hostname
• azure-init --set-hostname

Additional information

This should not be an exclusive flag. We would like the ability to use multiple flags in a call (--set-hostname --configure-sshd)