Pause and PLR refinements

- Move `pause_print` argument `unload_length` after `show_lcd` so it's next to `DXC_ARGS`.
- Tweak the position and conditions of PLR save in `resume_print`.
- Add `Nozzle::park_mode_0_height` accessor to get the raised Z height.
- Remove extraneous `recovery.save` from `dwin.cpp`.
- Move PLR `info.volumetric...` to `flag`.
- Remove some G-code spaces in PLR code
- Document `pause.h` function declarations.

Marlin/src/gcode/feature/pause/M125.cpp

@@ -80,7 +80,7 @@ void GcodeSuite::M125() {
 
   TERN_(POWER_LOSS_RECOVERY, if (recovery.enabled) recovery.save(true));
 
-  if (pause_print(retract, park_point, 0, show_lcd)) {
+  if (pause_print(retract, park_point, show_lcd, 0)) {
     if (ENABLED(EXTENSIBLE_UI) || !sd_printing || show_lcd) {
       wait_for_confirmation(false, 0);
       resume_print(0, 0, -retract, 0);

Marlin/src/gcode/feature/pause/M600.cpp

@@ -149,7 +149,7 @@ void GcodeSuite::M600() {
     #endif
   );
 
-  if (pause_print(retract, park_point, unload_length, true DXC_PASS)) {
+  if (pause_print(retract, park_point, true, unload_length DXC_PASS)) {
     #if ENABLED(MMU2_MENUS)
       mmu2_M600();
       resume_print(slow_load_length, fast_load_length, 0, beep_count DXC_PASS);