Add copy to S3Template

[zambrinf]

Type: Feature

When uploading a gzip file via another API it doesn't create the "Content-Encoding" metadata automatically, so I have to copy the file adding the contentEncoding parameter using S3Client.

Describe the solution you'd like
Add a method to execute Copy on S3Template passing the source/destination buckets and keys and possibly the Content-Encoding parameter.

Describe alternatives you've considered
Alternative is using S3Client directly, but more verbose.

May I try to work on this?

[maciejwalkowiak]

@zambrinf thanks for reporting. Before submitting a PR, can you propose how the API will look like?

[zambrinf]

@maciejwalkowiak something like String sourceBucket, String sourceKey, String destBucket, String destKey, Map<String, String> metadata, but for the content-encoding you can't just pass as metadata, you need to use CopyObjectRequest.Builder's .contentEncoding("someEncoding") method. Would be good if it's extendable to other parameters like contentType, contentLanguage, etc, probably checking if they are present and then setting in the builder. Maybe another Map parameter with keys being an Enum? Any thoughts?