s3: implement artifact range requests

[zyga]

The basic itent is to allow expressing an input stream for a fragment that corresponds to a single range request.

This patch is not ready to land, because it requires lock-step update in HawkBit proper. The long story short, is that the current abstraction of getFileInputStream is just insufficient to efficiently implement range requests for artifacts.

There are two goals for efficiency:

• We should not request or discard data we do not need
• We read all the data we requested and close the stream properly

The second problem is somewhat elusive, since S3 input stream has a close() method that informs us of incorrect usage if not all content is drained, when S3 is sending the content but are are not reading.

Corresponging HawkBit change is posted to HawkBit in a separate patch.

Fixes: https://github.com/eclipse/hawkbit-extensions/issues/91