Add support for S3 bucket location

[anjo-swe]

Use Case

We want to check the region of a S3 bucket

Example

describe s3_bucket('my-bucket') do
  it { should have_location('us-east-1') }
end

References

• https://docs.aws.amazon.com/sdk-for-ruby/v2/api/Aws/S3/Client.html#get_bucket_location-instance_method
• https://docs.aws.amazon.com/sdk-for-ruby/v2/api/Aws/S3/Types/GetBucketLocationOutput.html

Buckets in Region us-east-1 have a LocationConstraint of null.

Maybe handle null and return us-east-1 in that case