add json and yaml output format

[nabuskey]

This adds json and yaml output options to the get command. I need this functionality for e2e tests I am trying to add because I need to be able to parse command outputs programmatically.

./idpbuilder get secrets -o json
[
  {
    "name": "argocd-initial-admin-secret",
    "namespace": "argocd",
    "data": {
      "password": "abc",
      "username": "admin"
    }
  },
  {
    "name": "gitea-credential",
    "namespace": "gitea",
    "data": {
      "password": "abc",
      "username": "giteaAdmin"
    }
  }
]

[nimakaviani]

Neat!