Avoid media indexing on Android
Avoid media indexing on Android

Summary:
Record Android screen captures into a separate directory with a `.nomedia`
file to avoid it from getting indexed before it gets removed after being
pulled.

Reviewed By: danielbuechele

Differential Revision: D13465448

fbshipit-source-id: 4449ff3a927cc8621b015b018d2b743cedc4ce8c

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