[blob-service] Implement upload logic with new db
Summary:
Part of ENG-4269.
The code is mostly a copy-paste from http::handlers::blob::upload_blob_handler with the exception that it now accepts a stream instead of multipart form
Depends on D8454.
Test Plan: Tested later in the stack
Reviewers: michal, varun, jon, patryk
Reviewed By: michal
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D8455