[native] Use CommUtilsModule for encrypted media

Summary:
This diff replaces slow JS file <-> ArrayBuffer operations with the C++ ones from CommUtilsModule.

This resolves ENG-3408.

Depends on D7486

Test Plan:
Cleared media cache.
Sent encrypted media (both photo and video) from native. Was able to decrypt and view the messages.

Reviewers: marcin, atul

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D7515