SilkFX: enable sharing to the app.

SilkFX previously enabled VIEW intent, so you could "open with" the app
on an image file for the Gain Map viewer. This change also adds support
for the SEND intent, so you can "share to" the app from other apps.

Bug: 280608957
Test: Share to works from Files and Photos, open with still works.
Change-Id: If647471fcf10ce6395300a9c38aa7e05379dfe85