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/lcd/dwin/e3v2/dwin.cpp

@@ -2298,9 +2298,6 @@ void HMI_PauseOrStop() {
       if (HMI_flag.select_flag) {
         HMI_flag.pause_action = true;
         ICON_Continue();
-        #if ENABLED(POWER_LOSS_RECOVERY)
-          if (recovery.enabled) recovery.save(true);
-        #endif
         queue.inject_P(PSTR("M25"));
       }
       else {