New kernel drivers and more (#560)

- Added kernel base drivers for: display, pointer (touch, mouse, etc.), keyboard, adc, power supply and backlight
- Implement new kernel driver modules: `st7789-module` and `gt911-module`
- Implement ESP32 ADC "oneshot" kernel driver
- Implement ESP32  backlight kernel driver with ledc API
- Implemented `battery-sense` driver that allows for voltage measurement and creates a power supply child device
- Updated github actions
- Updated flash scripts
- Fix for esp32 legacy driver conflict with ADC
- Created separate `lilygo-tdeck` and `lilygo-tdeck-plus` devices
- Created `lilygo-module` with LilyGO kernel drivers
- Fix for intermittent errors in build related to code generation of `devicetree.c`
- `lvgl-module` can now map kernel drivers onto LVGL devices
- Created `KernelDisplayApp` as a mirror of `HalDisplayApp` (formerly `DisplayApp`)
- Removed `struct` and `enum` prefix in a lot of kernel driver cpp source files
- `lilygo-tdeck` and `lilygo-tdeck-plus` are now fully relying on kernel drivers and don't use any of the old HAL

Buildscripts/DevicetreeCompiler/source/generator.py

@@ -79,6 +79,11 @@ def property_to_string(property: DeviceProperty, devices: list[Device]) -> str:
                 value_list.append(str(item))
         return "{ " + ",".join(value_list) + " }"
     elif type == "phandle":
+        # Mirrors the string-passthrough convention "phandles" already uses for sentinel defaults
+        # like GPIO_PIN_SPEC_NONE: a binding default of "NULL" represents "no device referenced",
+        # not an actual node name to resolve.
+        if isinstance(property.value, str) and property.value == "NULL":
+            return "NULL"
         return find_phandle(devices, property.value)
     elif type == "phandles":
         value_list = list()