[native] Extract LoadableImage component

Summary: Addressing feedback from https://phab.comm.dev/D7225 - extracted the common part from <RemoteImage> to a new component: <LoadableImage>

Test Plan: Media images are still loaded and displayed correctly.

Reviewers: ashoat, atul, ginsu

Reviewed By: ashoat, atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D7232