Avoids deadlock when applying preferred activities

Prior to this change, we were resolving the mime type of a given intent
while holding the package lock. With this change, we instead rely on the
preferred-activity declaration to define the mime type if it's
important, removing need for an activity manager service call and the
potential for deadlock.

Bug: 143105100
Test: Manual; sideload to /system/etc/preferred-apps/ and reset app preferences
Change-Id: Ie0b124216b49a1147bd5c2e82cf8c7cadb3f08ac