Support for VPC endpoints

I wonder if it is possible to add support for VPC url endpoints to fence_aws. It checks against the standard service url, for example ec2.amazonaws.com, but if traffic needs to be kept inside the VPC it would be better to check against the EC2 VPC endpoint like for example vpce-abc123-xyz789.ec2.us-east-1.vpce.amazonaws.com. This will benefit setups where internet access is restricted.
Thank you,
Noe

No file or test is named in the issue, so first locate the fence_aws entry point and read how it checks the standard EC2 service URL. Trace where the endpoint is selected; done means a VPC endpoint such as the example can be used for setups that restrict internet access.

Written by the indexing model from the issue text.