Add new image tags commands

[cmoog]

Creates a new hidden command for managing image tags. coder tags

operate on Coder image tags

Usage:
  coder tags [command]

Available Commands:
  create      add an image tag
  ls
  rm          remove an image tag

Flags:
  -h, --help   help for tags

Global Flags:
  -v, --verbose   show verbose output

Use "coder tags [command] --help" for more information about a command.