Add support for S3 Access Points. This provides extra security as it
ensures applications are not working with buckets belong to third parties.
To bind a bucket to an access point, set the access point (ap) ARN,
which must be done for each specific bucket, using the pattern
fs.s3a.bucket.$BUCKET.accesspoint.arn = ARN
* The global/bucket option `fs.s3a.accesspoint.required` to
mandate that buckets must declare their access point.
* This is not compatible with S3Guard.
Consult the documentation for further details.
Contributed by Bogdan Stolojan
b7c2864613