Touch UI Bed Mesh Screen refactor, enhancements (#21521)

- Split mesh view and edit screen into two screens
- The editor now live-updates the graphics
- Added Touch UI mesh progress feedback to `G26`
- Show positive / negative mesh values in different colors

Marlin/src/lcd/extui/ui_api.h

@@ -168,10 +168,14 @@ namespace ExtUI {
       inline void onMeshUpdate(const xy_int8_t &pos, const_float_t zval) { onMeshUpdate(pos.x, pos.y, zval); }
 
       typedef enum : uint8_t {
-        MESH_START,    // Prior to start of probe
-        MESH_FINISH,   // Following probe of all points
-        PROBE_START,   // Beginning probe of grid location
-        PROBE_FINISH   // Finished probe of grid location
+        G29_START,        // Prior to start of probe
+        G29_FINISH,       // Following probe of all points
+        G29_POINT_START,  // Beginning probe of grid location
+        G29_POINT_FINISH, // Finished probe of grid location
+        G26_START,
+        G26_FINISH,
+        G26_POINT_START,
+        G26_POINT_FINISH
       } probe_state_t;
       void onMeshUpdate(const int8_t xpos, const int8_t ypos, probe_state_t state);
       inline void onMeshUpdate(const xy_int8_t &pos, probe_state_t state) { onMeshUpdate(pos.x, pos.y, state); }