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/libs/nozzle.cpp

@@ -225,6 +225,18 @@ Nozzle nozzle;
 
 #if ENABLED(NOZZLE_PARK_FEATURE)
 
+  float Nozzle::park_mode_0_height(const_float_t park_z) {
+    // Apply a minimum raise, if specified. Use park.z as a minimum height instead.
+    return _MAX(park_z,                       // Minimum height over 0 based on input
+      _MIN(Z_MAX_POS,                         // Maximum height is fixed
+        #ifdef NOZZLE_PARK_Z_RAISE_MIN
+          NOZZLE_PARK_Z_RAISE_MIN +           // Minimum raise...
+        #endif
+        current_position.z                    // ...over current position
+      )
+    );
+  }
+
   void Nozzle::park(const uint8_t z_action, const xyz_pos_t &park/*=NOZZLE_PARK_POINT*/) {
     constexpr feedRate_t fr_xy = NOZZLE_PARK_XY_FEEDRATE, fr_z = NOZZLE_PARK_Z_FEEDRATE;
 
@@ -237,15 +249,9 @@ Nozzle nozzle;
         do_blocking_move_to_z(_MIN(current_position.z + park.z, Z_MAX_POS), fr_z);
         break;
 
-      default: {
-        // Apply a minimum raise, overriding G27 Z
-        const float min_raised_z =_MIN(Z_MAX_POS, current_position.z
-          #ifdef NOZZLE_PARK_Z_RAISE_MIN
-            + NOZZLE_PARK_Z_RAISE_MIN
-          #endif
-        );
-        do_blocking_move_to_z(_MAX(park.z, min_raised_z), fr_z);
-      } break;
+      default: // Raise by NOZZLE_PARK_Z_RAISE_MIN, use park.z as a minimum height
+        do_blocking_move_to_z(park_mode_0_height(park.z), fr_z);
+        break;
     }
 
     do_blocking_move_to_xy(

Marlin/src/libs/nozzle.h

@@ -83,6 +83,7 @@ class Nozzle {
 
   #if ENABLED(NOZZLE_PARK_FEATURE)
 
+    static float park_mode_0_height(const_float_t park_z) _Os;
     static void park(const uint8_t z_action, const xyz_pos_t &park=NOZZLE_PARK_POINT) _Os;
 
   #endif