[native] Fix encrypted media upload on Android

Summary: This addresses ENG-9015.

Test Plan:
Confirm that upload of .dat files on Android no longer triggers the following error:

'upload failed', [Error: Failed to upload blob: guessContentTypeFromName(file.name) must not be null], undefined, undefined

Reviewers: bartek

Reviewed By: bartek

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13040