Devicetree DTS and YAML format improvements (#492)

* **DevicetreeCompiler**
  * Binding properties now support default values.
  * Compiler returns meaningful exit codes and reports errors more clearly.
  * Stronger validation of device configurations with unified error handling.
  * Added integration tests and a dedicated Devicetree test workflow.

* **Changes**
  * Platform binding schemas updated: some fields made required, others gained explicit defaults.
  * Many device-tree files simplified by removing unused/placeholder pin and transfer-size entries.

* **Documentation**
  * Removed several outdated TODO items.

Platforms/PlatformEsp32/Bindings/espressif,esp32-spi.yaml

@@ -13,11 +13,11 @@ properties:
       Defined by spi_host_device_t (e.g. SPI2_HOST, SPI3_HOST).
   pin-mosi:
     type: int
-    required: true
+    default: GPIO_PIN_NONE
     description: MOSI (Data 0) pin
   pin-miso:
     type: int
-    required: true
+    default: GPIO_PIN_NONE
     description: MISO (Data 1) pin
   pin-sclk:
     type: int
@@ -25,12 +25,15 @@ properties:
     description: Clock pin
   pin-wp:
     type: int
+    default: GPIO_PIN_NONE
     description: WP (Data 2) pin
   pin-hd:
     type: int
+    default: GPIO_PIN_NONE
     description: HD (Data 3) pin
   max-transfer-size:
     type: int
+    default: 0
     description: |
       Data transfer size limit in bytes. 
       0 means the platform decides the limit.