Fix injected settings titles not matching a locale change.

The injected tiles code currently treats the string metadata value
for the title key in the Activity's manifest as the title itself.
When the language on the device is changed the title remains in the
previous language until a reboot.

This CL will make injected tiles attempt to treat the string metadata
value as a resource variable to get the integer res id and then
properly load the localized title using the res id. To be backwards
compatible, if the res id is 0, we treat the string metadata value as
the title itself (current behavior).

Bug:36470694
Test: make RunSettingsLibRoboTests
Change-Id: I3963534a3a3a27d0455c4ed1ad4fa574b03d67fc