Add kernel drivers for SPI and UART and make locking APIs more consistent (#489)

- Add kernel support for SPI driver
- Add kernel support for UART driver
- Implemented ESP32 UART kernel driver
- Update existing UART-related code in Tactility to use new kernel driver
- Remove UART from tt::hal::Configuration
- Remove tt_hal_uart functionality but keep functions for now
- Update devicetrees for UART changes
- Kernel mutex and recursive mutex: improved locking API design
- Other kernel improvements
- Added device_exists_of_type() and device_find_by_name()

TactilityKernel/Source/drivers/gpio_controller.cpp

@@ -32,7 +32,7 @@ error_t gpio_controller_get_pin_count(struct Device* device, uint32_t* count) {
     return GPIO_DRIVER_API(driver)->get_pin_count(device, count);
 }
 
-extern const struct DeviceType GPIO_CONTROLLER_TYPE {
+const struct DeviceType GPIO_CONTROLLER_TYPE {
     .name = "gpio-controller"
 };