feat: Read API key and Account ID from envars

[AJCandfield]

What problem does this feature solve?

Most providers read authentication information from the environment.

How would you implement this feature?

https://github.com/cloudsmith-io/terraform-provider-cloudsmith/blob/aebcdd49c0f1e6695fddfd4f75e12e41d5659661/cloudsmith/provider.go#L21

[sorccu]

Hi,

We already do the same thing here:

terraform-provider-checkly/checkly/provider.go

Lines 17 to 31 in 4df14b8

	"api_key": {
	Type: schema.TypeString,
	Required: true,
	DefaultFunc: schema.EnvDefaultFunc("CHECKLY_API_KEY", nil),
	},
	"api_url": {
	Type: schema.TypeString,
	Optional: true,
	DefaultFunc: schema.EnvDefaultFunc("CHECKLY_API_URL", nil),
	},
	"account_id": {
	Type: schema.TypeString,
	Optional: true,
	DefaultFunc: schema.EnvDefaultFunc("CHECKLY_ACCOUNT_ID", nil),
	},

However, they are not documented. Could you try them out and see if they work for you?