Add Amazon S3 manager EMS

[aiperon]

Register S3 with the ext management system.
Similar to #13539.

Depends on ManageIQ/manageiq-providers-amazon#106.

Reqiured to CI tests pass.

@miq-bot add_label providers/amazon,providers/storage

[miq-bot]

Checked commit xlab-si@38ae9dc with ruby 2.2.6, rubocop 0.46.0, and haml-lint 0.19.0
1 file checked, 0 offenses detected
Everything looks good. 🍰

[miq-bot]

This pull request is not mergeable. Please rebase and repush.

[Fryguy]

Not sure I like the fact that the manager takes the toplevel s3 name...I would have expected ec2_object_storage . cc @roliveri . The corresponding PR in amazon was merged already by @Ladas but this one is now blocking ManageIQ from going green. Thoughts?

[gberginc]

@aiperon should be closed due to the combined PR related to the S3 changes #13580

[Ladas]

@Fryguy I think they just follow OpenStack way, where they've renamed it to CinderManager and SwiftManager, according to the name of the service. So not sure what was the motivation really. :-)

But then it fits to call the AWS managers according to the name of the service, so we are consistent there.

I would prefer Provider::Object/BlockStorage, as it will be more understandable across providers. :-)

[aiperon]

I think the only reason for ec2_object_storage is that StorageManager::S3 is a child provider of EC2 provider. Although, instead of EBS, S3 is not related to EC2 naturally.
Child provider Implementation was minimal change to getting things done. Otherwise, we had to define the way to add storage manager separately from cloud manager. At this moment there isn't full picture of how it should look's like.

[roliveri]

@Fryguy _ We discussed this. Didn't we agree that concrete names are better, enabling the support different implementations of a given type of storage (Block, Object, etc).

So Provider::Object/BlockStorage, Provider::Object/BlockStorage and ec2_object_storage would be wrong. Even if the chances are less likely in the Amazon environment that they'll have multiple implementations, we should still be consistent with the other storage managers. In addition Amazon instances can access external storage subsystems that provide the same type of storage - block for example, and we'll have to differentiate between those managers as well.