Migrate to the Terraform Plugin Framework

[DXTimer]

In order to ensure that we can leverage the most up-to-date features that Terraform provider and our users can benefit from the improvements in the provider framework, this PR migrates the provider from the SDKv2 to Terraform Plugin Framework.

In this PR we have touched all resources and data sources:

• Resource dnsimple_lets_encrypt_certificate:

  • The deprecated contact_id field has been removed from the dnsimple_lets_encrypt_certificate resource.
  • The id field on the dnsimple_lets_encrypt_certificate is now of type int64 instead of string to keep in line with the API.
  • The domain_id field on the dnsimple_lets_encrypt_certificate is now required.
  • The expires_on attribute on the dnsimple_lets_encrypt_certificate has been renamed to expires_at to keep in line with the API.

• Resource dnsimple_zone_record:

  • The ttl and priority fields on the dnsimple_zone_record are now of type int64 instead of string.

• Resource dnsimple_record:

  • The resource has been removed from the provider as it was deprecated in v0.9.2.

• The PREFETCH environment variable has been renamed to DNSIMPLE_PREFETCH to avoid conflicts with other services.