Add importer for startup script

[teh-username]

Test Plan:

Given .tf file:

provider "vultr" {
  api_key = "<api-key>"
}

resource "vultr_startup_script" "example" {
  content   = "#!/bin/bash echo Hello World > /root/hello"
  name      = "example"
  type      = "boot"
}

Running terraform import vultr_startup_script.example SCRIPTID yields:

vultr_startup_script.example: Importing from ID "SCRIPTID"...
vultr_startup_script.example: Import complete!
  Imported vultr_startup_script (ID: SCRIPTID)
vultr_startup_script.example: Refreshing state... (ID: SCRIPTID)

Import successful!

The resources that were imported are shown above. These resources are now in
your Terraform state and will henceforth be managed by Terraform.

Running terraform plan yields:

Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

vultr_startup_script.example: Refreshing state... (ID: SCRIPTID)

------------------------------------------------------------------------

No changes. Infrastructure is up-to-date.

This means that Terraform did not detect any differences between your
configuration and real physical resources that exist. As a result, no
actions need to be performed.

[squat]

Looks very good overall. I have two small comments. Fix those and let’s merge it.

[squat]

Nit: could you fix the casing of “Startup Script” to be lowercase to match the other log statements like https://github.com/squat/terraform-provider-vultr/blob/master/vultr/resource_startup_script.go#L97

[squat]

Nit: could you reverse the order of these operands? I think it’s geberally easier to read if the subject of the comparison, in this case script, comes first