Support remote terraform modules in custom-terraform

[Nitin Aggarwal]

Ability to refer to external terraform modules like the modules here: https://registry.terraform.io/browse/modules

This would enable the users to not rely on Opta modules for every infrastructure piece out there

[Nitin Aggarwal]

Checkout the docs here: https://docs.opta.dev/reference/aws/environment_modules/custom-terraform/