provider/scaleway: add scaleway_bucket resource

[nicolai86]

This PR adds a new resource to the Scaleway provider: scaleway_bucket.

This can be merged once Scaleway objectstorage is out of GA.

make testacc TESTARGS="-run='TestAccScalewayBucket'"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test $(go list ./... |grep -v 'vendor') -v -run='TestAccScalewayBucket' -timeout 120m
?   	github.com/terraform-providers/terraform-provider-scaleway	[no test files]
=== RUN   TestAccScalewayBucket
--- PASS: TestAccScalewayBucket (13.35s)
PASS
ok  	github.com/terraform-providers/terraform-provider-scaleway/scaleway

The PR includes docs, tests as well as the resource itself.

[tombuildsstuff]

hey @nicolai86

Left a couple of comments in-line - but this otherwise LGTM 👍

Thanks!

[tombuildsstuff]

so if this returns a not found error (e.g. a 404) we should clear the ID so this is detected and can be recreated e.g.

if err != nil {
  if resp.StatusCode == 404 {
    log.Printf("[DEBUG] Bucket %q was not found - removing from state!", name)
    d.SetId("")
    return nil
  }
}

[tombuildsstuff]

we don't need to clear the ID here

[nicolai86]

@tombuildsstuff thanks for taking a look. I've addressed the feedback - would you mind another look?

[tombuildsstuff]

LGTM 👍