implement the activity system

src/main/java/emu/grasscutter/game/activity/ActivityWatcher.java

@@ -0,0 +1,26 @@
+package emu.grasscutter.game.activity;
+
+import emu.grasscutter.data.excels.ActivityWatcherData;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.Setter;
+import lombok.experimental.FieldDefaults;
+
+@Getter
+@Setter
+@FieldDefaults(level = AccessLevel.PRIVATE)
+public abstract class ActivityWatcher {
+    int watcherId;
+    ActivityWatcherData activityWatcherData;
+    ActivityHandler activityHandler;
+
+    protected abstract boolean isMeet(String... param);
+
+    public void trigger(PlayerActivityData playerActivityData, String... param){
+        if(isMeet(param)){
+            playerActivityData.addWatcherProgress(watcherId);
+            playerActivityData.save();
+        }
+    }
+
+}