S3 external storage id always assumes Amazon is used

[PVince81]

Nowadays people use S3 also outside of Amazon, for example with Minio instances.

However the current code is always assuming we're using Amazon and creates it id only based on the bucket name: https://github.com/owncloud/core/blob/v10.0.10/apps/files_external/lib/Lib/Storage/AmazonS3.php#L116

• We should redesign the storage id to be composed of hostname + region + bucket name.

• A migration must be written that converts all existing storage ids in oc_storages from S3 to the new format. This will need to iterate over all the external storage configurations.

@DeepDiver1975 @butonic

[ownclouders]

GitMate.io thinks possibly related issues are #14371 (Issue adding S3 External Storage), #10198 (External Only Storage), #13147 (External Storage S3 Very High Requests), #11652 (Amazon S3 not updating), and #26819 ([External Storage] Amazon S3 uploaded folders via AWS console are not available in ownCloud).