Allow NPC view data modifications (#4385)

* Fixes #4289.
* Updated script commands setunitdata and getunitdata to support the modification of NPC view data.
* Converted mob_avail database to YAML.
Thanks to @Lemongrass3110, @4144, @exneval, @Balferian, @cahya1992 and @teededung!
Co-authored-by: Lemongrass3110 <lemongrass@kstp.at>

src/map/unit.cpp

@@ -3134,6 +3134,26 @@ int unit_remove_map_(struct block_list *bl, clr_type clrtype, const char* file,
 	return 1;
 }
 
+/**
+ * Refresh the area with a change in display of a unit.
+ * @bl: Object to update
+ */
+void unit_refresh(struct block_list *bl) {
+	nullpo_retv(bl);
+
+	if (bl->m < 0)
+		return;
+
+	struct map_data *mapdata = map_getmapdata(bl->m);
+
+	// Using CLR_TRICKDEAD because other flags show effects
+	// Probably need to use another flag or other way to refresh it
+	if (mapdata->users) {
+		clif_clearunit_area(bl, CLR_TRICKDEAD); // Fade out
+		clif_spawn(bl); // Fade in
+	}
+}
+
 /**
  * Removes units of a master when the master is removed from map
  * @param sd: Player