Allow specifying S3 region in file.managed requests

[keslerm]

One thing we are heavily struggling with is that we use buckets in specific regions that each minion has access to but there is no way to specify the region of that specific bucket in a file.managed stanza in a state so the minion will just default to a region and it will be wrong.

We can't just set the region for the minion specifically because it's connecting to multiple different regions.

There should be some mechanism for setting the region in each request.

[bdrx312]

This would be a good feature to have, but as a work around you may be able to utilize s3 access points https://aws.amazon.com/s3/features/access-points/. Also you probably want instances to access buckets in the same region as the bucket otherwise you incur much higher transfer times/latency and also have to pay extra cross region data transfer costs.