Remove send/send multiple if intent doesn't resolve to any activity

Instead of falling back to the editor activity as a last resort for "Send",
remove the option if there's no potential candidate.  The editor activity won't
handle the ACTION_SEND/ACTION_SEND_MULTIPLE intent anyway.  This stops an error
from popping up in the editor if the file cannot be sent from any other activity.

FEIJ-1380
Change-Id: I2330299e0cb8b6f3c93d5a190067b8bfe6a3f56f