Messaging ignores file URIs shared via intent

Fixes b/37629504 by not creating attachments from file URIs shared via
intent. Sharing file URIs is disallowed by Android N and later and is no
longer supported for this app.

Test: manual using the Debug command added in this change

Change-Id: Ibff486c94ac703a9a4c5a80e33b934a460804a8f
Merged-In: Ibff486c94ac703a9a4c5a80e33b934a460804a8f
(cherry picked from commit 9deefdf182d69f98d361d9d24de1e4892923dac5)
2 files changed