Polish sos gesture behind the lockscreen

Unlike camera, we only want one intent for the emergency action (rather
than a secure / insecure breakdown). The api startActivity didn't work
behind the keyguard (WAI, I believe) so this CL changes that approach
to start the activity more traditionally.

The existing test is unfortunately removed. In its implementation CL,
[ag/12721582] dupin@ and I discussed the best way to test the action
given we would either check the activity was started with the context
[mContext.startActivity] or from the ActivityStarter
[StatusBar#startActivity]. Unfortunately ActivityStarter doesn't work
for our use case given the Keyguard gets raised (what we're trying to
fix in this CL), so we're left with verifying the injected Context gets
called. In theory we could add a wrapper method and verify it gets
called, but that seems next-to-useless.

Bug: 172278542
Fixes: 171084088
Fixes: 175240607
Test: atest StatusBarTest

Change-Id: Idd855be8d8c9fd35691c32bf88b3b9e2cdbc7b50