Launcher mode: Gearslip as the home screen of a head unit or a dash tablet

Turned on under Settings > Connection, Gearslip's car screen fills the device's own
display as its home app. An All apps page opens any other app full screen, Back and
a head unit's keys work the car UI, and Phone hides on devices that can't call.
Phones never see Gearslip offered as a home app unless it's switched on.

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

@@ -864,6 +864,12 @@
     <string name="status_no_car_graphene">The phone is charging, but no car has answered. Check that USB-C port control, under Security &amp; privacy, allows data and isn\'t set to Charging-only.</string>
     <string name="status_stuck_cable">The car hasn\'t shown Gearslip yet. Unplug the cable, wait a few seconds, and plug it back in. If it keeps happening, try another cable or USB port, and share the log in an issue.</string>
     <string name="status_stuck_wireless">The car hasn\'t shown Gearslip yet. Turn the car off and on again, or connect with a cable. If it keeps happening, share the log in an issue.</string>
+    <string name="settings_use_as_launcher">Use as launcher</string>
+    <string name="settings_use_as_launcher_off">For a head unit or a tablet on the dash. Gearslip\'s car screen becomes this device\'s home screen.</string>
+    <string name="settings_use_as_launcher_on">Gearslip can be this device\'s home screen. Pick it under Default home app.</string>
+    <string name="app_all_apps">All apps</string>
+    <string name="launcher_in_car">This device is connected to a car, so Gearslip is on the car\'s screen.</string>
+    <string name="launcher_open_gearslip">Open Gearslip</string>
     <string name="status_open_settings">Open settings</string>
     <string name="status_connecting">Connecting</string>
     <string name="status_projecting">Projecting</string>