Terraform plugin: Add support for OpenTofu

[zakuciael]

Platform or tool

Terraform

Desired or expected behavior

Support OpenTofu which is an open-source fork of Terraform.

Current behavior

Terraform plugin only works with terraform binary.

Relevant log output

No response

op CLI version

No response

[0x2b3bfa0]

Potentially related to #230

[skyqrose]

There is an open PR for this, which would create an entire duplicate plugin, rather than making the terraform plugin compatible with tofu: #553