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  * Removed several outdated TODO items.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-i2c.yaml

@@ -7,16 +7,20 @@ compatible: "espressif,esp32-i2c"
 properties:
   port:
     type: int
+    required: true
     description: |
       The port number, defined by i2c_port_t.
       Depending on the hardware, these values are available: I2C_NUM_0, I2C_NUM_1, LP_I2C_NUM_0
   clock-frequency:
     type: int
+    required: true
     description: Initial clock frequency in Hz
   pin-sda:
     type: int
+    required: true
   pin-scl:
     type: int
+    required: true
   pin-sda-pull-up:
     type: bool
     description: enable internal pull-up resistor for SDA pin

Platforms/PlatformEsp32/Bindings/espressif,esp32-i2s.yaml

@@ -21,13 +21,14 @@ properties:
     description: WS pin
   pin-data-out:
     type: int
-    required: true
+    default: GPIO_PIN_NONE
     description: DATA OUT pin
   pin-data-in:
     type: int
-    required: true
+    default: GPIO_PIN_NONE
     description: DATA IN pin
   pin-mclk:
     type: int
-    required: true
+    required: false
+    default: GPIO_PIN_NONE
     description: MCLK pin

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.

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

@@ -21,7 +21,9 @@ properties:
     description: RX pin
   pin-cts:
     type: int
+    default: GPIO_PIN_NONE
     description: CTS pin
   pin-rts:
     type: int
+    default: GPIO_PIN_NONE
     description: RTS pin