Improve/fix D23 for M2.5/S printers

- Move D23 into it's own function inside Dcodes
- Correctly include a break in the switch statement
- Show the dumper status (enabled/disabled) after toggling
- Allow to generate an immediate dump via g-code using D23 E for
  symmetry with D20 E

Firmware/Marlin_main.cpp

@@ -9382,12 +9382,14 @@ Sigma_Exit:
     When online dumps are enabled, the FW will dump memory on the serial before resetting.
     #### Usage
 
-     D23 [R]
+     D23 [E] [R]
     #### Parameters
+    - `E` - Perform an emergency crash dump (resets the printer).
     - `R` - Disable online dumps.
     */
     case 23: {
-        emergency_serial_dump = !code_seen('R');
+        dcode_23();
+        break;
     };
 #endif