[native] Fix sending videos on iOS 18

Summary: On iOS 18 getAssetInfoAsync returns uri with a weird #YnBsaXN... suffix. This looks like iOS bug so for now to mitigate it we simply remove the suffix.

Test Plan: Send video on iOS 18 and 15.

Reviewers: tomek, kamil, ashoat

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13786