Support environment variables in provider configuration

[sebastianreloaded]

To avoid saving credentials in the state file, it would be nice to have support for environment variables for e.g. username and password in the provider block.
Most other terraform providers support this.

https://registry.terraform.io/providers/airbytehq/airbyte/latest/docs

[ThomasRooney]

This is a fair ask. We will do this at some point. In the short term, a variable with sensitive = true that's imported from TF_VAR_{varName} is equivalent. https://developer.hashicorp.com/terraform/language/values/variables#environment-variables