Consider Aliases in the Registry

[cam72cam]

This is a more nuanced view of #87. https://developer.hashicorp.com/terraform/internals/archiving is also worth reading.

Related tofu code can be found here:
https://github.com/opentofu/opentofu/blob/5c1ecde90a1770cc2722aa9e21769422e6dd8491/internal/getproviders/didyoumean.go#L234
https://github.com/opentofu/opentofu/blob/5c1ecde90a1770cc2722aa9e21769422e6dd8491/internal/command/command_test.go#L1055
https://github.com/opentofu/opentofu/blob/5c1ecde90a1770cc2722aa9e21769422e6dd8491/internal/getproviders/registry_client_test.go#L241

Provider examples to consider:

source = "github"

This is mapped to hashicorp/github or opentofu/github by tofu, whichever is the default namespace.

Those paths imply the repository: https://github.com/hashicorp/terraform-provider-github. This repository is archived and a fork of the https://github.com/integrations/terraform-provider-github repository. This implies a redirect which can be confirmed using a recent version of terraform.

We now have an "Override" implemented in #87 that makes sure integrations/github is copied to hashicorp/github. This seems to match terraform's behavior.

source = "digitalocean"

This is mapped to hashicorp/digitalocean or opentofu/digitalocean by tofu, whichever is the default namespace.

Those paths imply the repository: https://github.com/hashicorp/terraform-provider-digitalocean. This repository is archived and a fork of the https://github.com/digitalocean/terraform-provider-digitalocean repository. This implies a redirect which is not confirmed using a recent version of terraform.

We now have an "Override" implemented in #87 that makes sure digitalocean/digitalocean is copied to hashicorp/digitalocean. This does not seems to match terraform's behavior. Instead running terraform suggests the digitalocean/digitalocean package as part of an error response.

This is part of the 0.13upgrade path that has been left in the 1.5.x code that was forked into opentofu. If a provider in the default namespace is not found, either hashicorp/digitalocean or digitalocean, a request is sent to the currently configured registry for "/v1/providers/-/digitalocean/versions". It then looks for a moved_to field in the response and uses that to build the error message.

Summary:

I do not understand why one of these is a redirect and one is an "alias". This temporary override in #87 opens up the question of how to properly support "moved_to" in tofu as a whole. There are limitations as it is unclear if we can duplicate the exact "moved_to" configurations. At the moment it is a best guess based on repository names / status as documented in #87.

Additionally, in #87 I did not synchronize the overrides to the opentofu namespace, which should be done soon.