Add support for setting profile like in the aws provider

[hoxu]

The Terraform aws provider allows setting AWS profile like this:

provider "aws" {
  profile = "customprofile"
}

Currently this Redshift provider does not allow that. The underlying aws-sdk-go-v2 implicitly uses the environment variable AWS_PROFILE if set.

This means that if you are using AWS profiles, you need to remember to run Terraform with AWS_PROFILE=customprofile terraform plan, or the GetClusterCredentials call will fail. This is pretty cumbersome.

I think it would be a good idea to add a top level configuration option to this Redshift provider, like this:

provider "redshift" {
  profile = "customprofile"
}

Implementing it should be pretty straight-forward unless I'm mistaken.

The aws-sdk-go-v2 allows specifying a profile explicitly:

cfg, err := config.LoadDefaultConfig(context.TODO(), 
	config.WithSharedConfigProfile("test-account"))

The provider schema would need to be expanded with the profile option:

terraform-provider-redshift/redshift/provider.go

Lines 24 to 26 in bbfe59a

	func Provider() *schema.Provider {
	return &schema.Provider{
	Schema: map[string]*schema.Schema{

The redshiftSdkClient function would need to pass the profile name to LoadDefaultConfig, if set, or else fall back to calling it as before:

terraform-provider-redshift/redshift/provider.go

Lines 234 to 235 in bbfe59a

	func redshiftSdkClient(d *schema.ResourceData) (*redshift.Client, error) {
	cfg, err := config.LoadDefaultConfig(context.TODO())