[keyserver] Upload both multimedia holder and blob_hash

Summary:
Resolves ENG-3962 and its subtasks. It turned out to be a one-line change on client side.
Basically, added a blobHash field to endpoint input types and passed it all the way down input-state-container -> uploadMediaMetadata endpoint -> createUploads() -> db

Test Plan: Enabled blob service uploads on web and uploaded a photo. Checked in TablePlus that both values are stored on the keyserver. Repeated for native.

Reviewers: atul, ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D8256