Support S3A cross region access when S3 region/endpoint is set

Currently when S3 region nor endpoint is set, the default region is set to us-east-2 with cross region access enabled. But when region or endpoint is set, cross region access is not enabled.

The proposal here is to carves out cross region access as a separate config and enable/disable it irrespective of region/endpoint is set. This gives more flexibility to the user.