feat(worldclock): show home time as text under the analog face

The World clock tab now prints the home time under the hero face in the
app's 12/24-hour format, reversing the earlier call to leave it out.
Reading the exact minute off a dial is slow, and that minute is what
most visits to the tab are for.

The face no longer has a content description, so TalkBack does not read
the time twice. The readout, "Home", the city and the zone name are one
merged node instead.

Closes #4

app/src/main/res/values/strings.xml

@@ -227,7 +227,6 @@
     <string name="world_clock_day_today">Today</string>
     <string name="world_clock_day_tomorrow">Tomorrow</string>
     <string name="world_clock_unknown_zone">This time zone is no longer on your device</string>
-    <string name="world_clock_face_description">%1$s, %2$s</string>
     <string name="world_clock_row_description">%1$s, %2$s, %3$s</string>
     <!-- A row whose zone the device no longer knows has no time to read out. -->
     <string name="world_clock_row_description_unknown">%1$s, %2$s</string>