Coder Secret Requirement

[evgeniy-scherbina]

Depends on #795

Changes to terraform-provider-coder:

Define new coder_secret data source.

data "coder_secret" "my_secret" {
	env = "MY_SECRET"
}

data "coder_secret" "my_secret" {
	file = "~/.my-file"
}

# secrets should be accessible in build-time:
coder_secret.my_secret.value

Schema should consist of 3 fields:

• env (optional)
• file (optional)
• value (readonly, sensitive)

Despite both env and file are optional, exactly one of them should be set.

Values should be populated from Environment Variables set by Build-time Secrets Injection process (see #795).

External auth data source is a good example how it can be implemented: https://github.com/coder/terraform-provider-coder/blob/main/provider/externalauth.go