Add grafana_k6_project_allowed_load_zones resource / data source

[pmdz]

Implement allowed load zones management for k6 projects.
Relevant k6 public API docs: link

1. Add grafana_k6_project_allowed_load_zones resource
2. Add grafana_k6_project_allowed_load_zones data source

Issue: https://github.com/grafana/k6-cloud/issues/3512

[CLAassistant]

All committers have signed the CLA.

[github-actions]

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[fornfrey]

Thanks a lot for the PR! I left a couple of suggestions regarding state management. Let me know if you have any questions or need help.

[yorugac]

Suggested change

	"allowed_load_zones": schema.ListAttribute{
	Description: "List of allowed k6 load zone IDs for this project.",
	"allowed_load_zones": schema.ListAttribute{
	Description: "List of allowed k6 private load zones (names) for this project.",

I've wondered about the naming here: this object is supposed to be only for configuring private LZs, in reality. AFAIK, this is not going to change in the future either.
Changing the allowed_load_zones to allowed_private_load_zones seems a bit too verbose ATM, but perhaps, at least the description could contain clarification?
cc @pmdz @fornfrey

[pmdz]

I've tweaked the description a little bit in b239626

This are not names btw., we're referencing the IDs here

[yorugac]

Thanks, Pawel!
From user's perspective, this can be confusing actually, because it's a name in Kubernetes resource. But in UI, we call it "ID" 😄 But you're right that this is a frontend level problem: I've brought it up before in the Slack too.
cc @dgzlopes for visibility: just in case, we should change this everywhere.

[fornfrey]

Well done! LGTM