* feat(middleware): introduce built-in Validator Middleware
* fixed type of `req.json()`
* Feat/builtin validator middleware another idea (#508)
* Enable overwriting of query/header data.
* Returns only verified data.
* rename `index.test.ts` to `middleware.test.ts`
* add `removeAdditional` option
* handling error that the JSON body is null
* tidy
* check is it string or not
* implement `isIn`
* enable validation the valies are duplicate
Co-authored-by: Taku Amano <taku@taaas.jp>
