Fix talking not progressing quests & Add talk execution handlers

src/main/java/emu/grasscutter/game/talk/exec/ExecSetQuestVar.java

@@ -0,0 +1,27 @@
+package emu.grasscutter.game.talk.exec;
+
+import emu.grasscutter.data.excels.TalkConfigData;
+import emu.grasscutter.data.excels.TalkConfigData.TalkExecParam;
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.game.quest.GameMainQuest;
+import emu.grasscutter.game.talk.TalkExec;
+import emu.grasscutter.game.talk.TalkExecHandler;
+import emu.grasscutter.game.talk.TalkValueExec;
+
+@TalkValueExec(TalkExec.TALK_EXEC_SET_QUEST_VAR)
+public final class ExecSetQuestVar extends TalkExecHandler {
+    @Override
+    public void execute(Player player, TalkConfigData talkData, TalkExecParam execParam) {
+        if (execParam.getParam().length < 3) return;
+
+        var mainQuest = player.getQuestManager().getMainQuestById(
+            Integer.parseInt(execParam.getParam()[2])
+        );
+        if (mainQuest == null) return;
+
+        mainQuest.setQuestVar(
+            Integer.parseInt(execParam.getParam()[0]),
+            Integer.parseInt(execParam.getParam()[1])
+        );
+    }
+}