Gamedata refactoring

[YongHee-Kim]

Description

1. Problems to solve. Make game data and localization data more easily manageable with Excel software. #1014 I've put all the datas outside of Unity to avoid generation of .meta which can be pain point to manage. Such as residual .metafiles from file structure change like this

2. Features to add. This is non breaking change, but CSV data loader need to be refactored to JSON data loader to use all functionality of GameDataManger. But you can export .csv data as well. Just make output file extension to .csv in config.json like this

        "MonsterCollection.xlsx": {
            "workSheets": [
                {
                    "name": "Sheet",
                    "out": "MonsterCollectionSheet.csv"
                }

How to test

There is no test yet, I've written install and usage instruction on README for game designers.

[CLAassistant]

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