FEAT: openprovider as a provider

[extremeshok]

would be nice to have openprovider as a provider

https://docs.openprovider.com/doc/all

[maelgangloff]

I've started an implementation for this registrar (feat/openprovider-provider branch).

However, I'm a bit stuck on the API call for domain name purchase. This will require testing to ensure the parameters included in the request are correct.

API documentation: https://docs.openprovider.com/doc/domain.swagger#operation/CreateDomain
And also here: https://docs.openprovider.com/doc/all#tag/descDomainQuickstart

For those who want to continue development, there's a dedicated documentation page explaining how to implement a new provider: https://domainwatchdog.eu/en/developing/implementing-new-provider/