Add tags commands

[mikesellitto]

This PR adds a doppler tags command group which will call our v3 tags endpoints once supported.

Note: Not to be merged until feature flag removal

Specifically, this PR:

• Adds doppler tags which lists tags
  • Adds get, create, update, and delete subcommands
    • create has optional flags --color and --slug
    • update requires at least one of --name or --color
    • delete prompts for confirmation unless -y is passed
• Adds a PatchRequest helper since the update endpoint is a PATCH and we only had PUT

Closes ENG-9686