[BUG] - Unable to set user data during reinstall

[rohankrishnadev]

Describe the bug
When I try to reinstall OS on an instance I can't seem to set user data. For example I have an instance with Ubuntu 20.04 installed and would like to change the OS to Fedora CoreOS which expects an ignition file during install. However there is no option to supply the ignition file when I change the OS.

To Reproduce
Steps to reproduce the behavior:

1. $ vultr-cli server os change --help gives you

changes operating system

Usage:
  vultr-cli server os change <instanceID> [flags]

Flags:
  -h, --help        help for change
  -o, --os string   operating system ID you wish to use

Global Flags:
      --config string   config file (default is $HOME/.vultr-cli.yaml)

Expected behavior
There needs to be an additional flag option for vultr-cli server os change <instanceID> [flags] where you can either pass in the user data or a file containing the user data.

Screenshots
N/A

Desktop (please complete the following information where applicable:

• OS: MacOS Catalina
• Vultr-CLI version: Vultr-cli v0.4.0

Additional context
N/A