feat: add fertilizer pump test functionality with web integration and HAL support

Software/MainBoard/rust/src/hal/v4_hal.rs

@@ -484,6 +484,15 @@ impl<'a> BoardInteraction<'a> for V4<'a> {
         Ok(())
     }
 
+    async fn extra2(&mut self, enable: bool) -> FatResult<()> {
+        if enable {
+            self.extra2.set_high();
+        } else {
+            self.extra2.set_low();
+        }
+        Ok(())
+    }
+
     async fn backup_config(&mut self, controller_config: &PlantControllerConfig) -> FatResult<()> {
         let mut buffer: [u8; 4096 - BACKUP_HEADER_MAX_SIZE] = [0; 4096 - BACKUP_HEADER_MAX_SIZE];
         let length = postcard::to_slice(controller_config, &mut buffer)?.len();