Integrate RHP4 for uploads

[ChrisSchinnerl]

This refers to integrating it in the most basic way to avoid a huge refactor of the upload code and to just get uploads working the same way they do now.

That means:

• if we are beyond the allow height and talking to a host version v2.0+, we use RHP4 for uploads
• partial uploads are still sent to the bus and later fetched for uploading when the pieces can be combined
• uploads are pinned blockingly, allowing us to avoid db changes initially