gts4lv-common: Map input-swap button to multitask

* Bind keycode 706 to APP_SWITCH.

* We lack framework stuff to toggle this cleanly,
  plus we already have onscreen input toggle button
  in navigation bar where soft-keyboard can be toggled.

* This is actually pretty nice, single click to app switcher,
  double click goes to last app.

Change-Id: I07419ccdad0acd920e35d23af24f78eb4465b2b7

keylayout/Vendor_04e8_Product_a035.kl

@@ -409,6 +409,8 @@ key 523   POUND
 key 580   APP_SWITCH
 key 582   VOICE_ASSIST
 
+key 706   APP_SWITCH
+
 # Keys defined by HID usages
 key usage 0x0c006F BRIGHTNESS_UP
 key usage 0x0c0070 BRIGHTNESS_DOWN