Allow S3 Binary Manager to run in async mode

Default implementation of BinaryManager is 100% Synchronous.
This means the calling thread will wait for :

• copy steam to temporary location
• compute digest
• store in S3 (potentially with cypher)
• wait for S3 aknowledgment

This behavior is safe, but may slow down Write operations.

The goal is to provide a Async version of the S3BinaryManager that delegate the "S3 flush" to a Worker.

We now have 2 implementation classes for S3 BinaryManager

Normal S3 BinaryManager (Sync)

nuxeo.core.binarymanager=org.nuxeo.ecm.core.storage.sql.S3BinaryManager

Async S3 BinaryManager

nuxeo.core.binarymanager=org.nuxeo.ecm.core.storage.sql.AsyncS3BinaryManager

Using the Async mode :

• is not TX safe
• is not safe in cluster mode