feat: Add edge commands

[maciaszczykm]

It adds edge commands:

$ plural edge image -h
NAME:
   plural edge image - prepares image ready to be used on Raspberry Pi 4

USAGE:
   plural edge image [command options] [arguments...]

OPTIONS:
   --project value        name of the project to use (default: "default")
   --user value           optional external user email to be the user identity for bootstrap token in audit logs
   --username value       name for the initial user account (default: "plural")
   --password value       password for the initial user account, required if cloud configuration file is not provided
   --wifi-ssid value      ssid of the wifi network
   --wifi-password value  password for the wifi network
   --output-dir value     output directory where the image will be stored (default: "image")
   --cloud-config value   path to cloud configuration file, if provided templating will be skipped
   --plural-config value  path to plural configuration file

$ plural edge bootstrap -h
NAME:
   plural edge bootstrap - registers edge cluster and installs agent onto it using the current kubeconfig

USAGE:
   plural edge bootstrap [command options] [arguments...]

OPTIONS:
   --machine-id value  the unique id of the edge device on which this cluster runs

See also https://github.com/pluralsh/edge.

[linear]

PROD-3106 utilize cluster registration apis to fully set up edge cluster

[michaeljguarino]

pre-emptively approving when you feel like it's stable enough to merge

[maciaszczykm]

@michaeljguarino I've tested it multiple times but I'll give it another try tomorrow and go through the code again. If I will not find anything then I'll merge it tomorrow.