[native] Update avatar hooks to support skipping keyserver upload

Summary:
Update avatar-hooks for uploading media to support a flag whether to upload metadata to keyserver. This bases on mechanism introduced in D13280

Depends on D13286

Test Plan: This is tested together with next diffs in the stack

Reviewers: kamil, tomek

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13294