Add Quests System and Quests Screen

[Jeremi360]

Describe Main Idea

Having Quests System/Screen would allow for player to easier comeback to game after long break.

Proposed Implementation

UI

This is from RPGMaker Plugin

Godot/GDScript

I think Quest as Resource would be good for that.
And then Quests Singleton will search for quests resurces in res://quests/ dir.

Quests.start("quest_id/sub_quest")
Quests.done("quest_id/sub_quest")

RKScript

start_quest quest_id/sub_quest
done_quest quest_id/sub_quest