resource_device_authorization: update delete

[defo89]

deletes the device on authorization resouce deletion

What this PR does / why we need it: Ability to delete device with provider

Which issue this PR fixes: fixes #68

[defo89]

Worth to mention: if multiple resources are created/destroyed in a single run, users may face an error that some resources failed to be destroyed (due to device being removed already).

data "tailscale_device" "device1" {
  name     = "device1"
  wait_for = "60s"
}

resource "tailscale_device_authorization" "authorization" {
  device_id  = data.tailscale_device.device1.id
  authorized = true
}

resource "tailscale_device_key" "key" {
  device_id           = data.tailscale_device.device1.id
  key_expiry_disabled = true
}

resource "tailscale_device_subnet_routes" "routes" {
  device_id = data.tailscale_device.device1.id
  routes = local.routes
}

› terraform destroy -auto-approve
---snip---
Error: Failed to set device subnet routes
internal server error (500)

Error: failed to update device key
internal server error (500)

User will have to make sure that device deletion happens last.

[davidsbond]

I'm still of the opinion that if the terraform provider is not in charge of creating devices then it seems like not the right place for deleting them.

However, should this PR be accepted we should probably update the documentation for this resource as part of this pull request to inform users of the behaviour if they delete the device_authorization resource.

IMO we should modify the description on line 14 to include this information, you'll also need to run go generate ./... after you modify it.

[davidsbond]

if multiple resources are created/destroyed in a single run, users may face an error that some resources failed to be destroyed (due to device being removed already).

This is part of the reason I don't like us managing deletion without creation, the UX suffers in a non-obvious way.