capture version_id after upload

[shcheklein]

Similar to fsspec/gcsfs#718

To be able to refer to a file properly (in case multiple uploads happening simultaneously to the same path), we want to grab generation from the response. S3 already does this.

[shcheklein]

@martindurant do you know by chance who is maintaining the project and could release this change?

[kyleknap]

@shcheklein thanks for contribution! Populating the updated version_id after a completed upload seems reasonable to me especially since s3fs is already doing this and you have a similar change out for gcsfs.

I'll have more cycles next week to take a deeper review but some initial things we probably want to address now are:

1. Let's populate the version_id only if the upstream file system is version_aware. Looks like s3fs has similar logic
2. It would be great if we can get test cases added to make sure we the version_id is getting set for the different upload branches where it is being set now for version aware filesystems. It would also be good to have a test case too where we don't set the version_id if the filesystem is not version aware.
3. Add a small changelog entry here for the enhancement.