[lib] Shim Blob service hosted multimedia
Summary:
Resolves ENG-3728. Old clients which do not support Blob service URIs should display a shim message. Otherwise, these media wouldn't be able to load.
Depends on D7615
Test Plan:
- Artifically replaced each URI parameter in keyserver upload-fetchers with fake Blob service URIs
- Log out and back in on native
- Verify that shim message is displayed
Reviewers: ashoat, atul
Reviewed By: ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D7616