New kernel drivers and device implementation updates (#561)

- Added modular device support and devicetree bindings for ILI9341, ILI9488, CST816S, XPT2046, and GPIO button input, updating several board configurations for display/touch/backlight/keyboard/battery.
- Added a setting to control deprecated HAL usage (device property + Kconfig).

Drivers/button-control-module/README.md

@@ -0,0 +1,30 @@
+# Button Control
+
+Kernel driver for navigating apps with 1 or 2 GPIO buttons. Kernel-driver counterpart to
+`Drivers/ButtonControl`, exposing a `KEYBOARD_TYPE` device (`tactility/drivers/keyboard.h`)
+instead of an LVGL encoder indev.
+
+Devicetree binding: `tactility,button-control` (see `bindings/tactility,button-control.yaml`).
+
+## Modes
+
+- **One-button** (`pin-secondary` absent): short press = `LV_KEY_NEXT`, long press = `LV_KEY_ENTER`.
+- **Two-button** (`pin-secondary` present): primary short = `LV_KEY_ENTER`, primary long =
+  `LV_KEY_ESC`, secondary short = `LV_KEY_NEXT`, secondary long = `LV_KEY_PREV`.
+
+Short vs. long press is only decided when the button is released, by comparing the hold
+duration against `long-press-ms` - not at the moment it's pressed.
+
+## Example
+
+```dts
+buttons {
+    compatible = "tactility,button-control";
+    pin-primary = <&gpio0 37 GPIO_FLAG_NONE>;
+    pin-secondary = <&gpio0 39 GPIO_FLAG_NONE>;
+};
+```
+
+## License
+
+[Apache License Version 2.0](LICENSE-Apache-2.0.md)