New board: Elecrow CrowPanel Advance 3.5" (#231)

- Implement CrowPanel Advance 3.5"
- New driver subproject: ILI9488
- New driver subproject: GT911
- Refactor T-Deck to use new driver subproject
- Fix for `flash.ps1`: don't set flash speed

Tactility/Source/service/gui/Gui.cpp

@@ -40,6 +40,7 @@ Gui* gui_alloc() {
     tt_check(lvgl::lock(1000 / portTICK_PERIOD_MS));
     instance->keyboardGroup = lv_group_create();
     auto* screen_root = lv_scr_act();
+    assert(screen_root != nullptr);
 
     lvgl::obj_set_style_bg_blacken(screen_root);