refactor(gui): drop setFullscreen now that chrome is a Lua node

Fullscreen was the firmware surrendering a strip it clipped apps out of.
The strip is a sibling node now, so an app that wants the panel is chrome
choosing not to build itself.

native/src/bindings/core/gui.cpp

@@ -125,12 +125,6 @@ int roundRect(lua_State* state) {
   return 0;
 }
 
-int setFullscreen(lua_State* state) {
-  luaL_checkany(state, 1);
-  provider(state).setFullscreen(lua_toboolean(state, 1) != 0);
-  return 0;
-}
-
 void readIntegers(lua_State* state, int index, std::vector<int32_t>& out) {
   const lua_Integer count = luaL_len(state, index);
   for (lua_Integer at = 1; at <= count; at++) {
@@ -291,9 +285,6 @@ const luaL_Reg FUNCTIONS[] = {
     // without a gradient use top.
     // @param border GuiColor|nil Omitted for no border.
     {"roundRect", roundRect},
-    // ---Temporarily gives the app the full panel, including firmware chrome.
-    // @param on boolean
-    {"setFullscreen", setFullscreen},
     // --- Fills a polygon.
     // @param xs integer[]
     // @param ys integer[]