Buffer property return TEXT instead of buffer

Bug or feature request

• Bug
• Feature request

Description of feature (or steps to reproduce if bug)

Currently, I am using this with loopback4. But the connector does not provide some type support such as, Buffer or Array. They will all turn into TXET in sqlite3. And more importantly, the 'Buffer' seems to work quite well. When i wrote something to a 'Buffer' property, it will ture in to some TEXT like

{ type: 'Buffer',
  data: 
   [ 120,
     156,
     237,
     205,
     59,
]
```.
And I when i retrieve it is still a JSON object instead of a Buffer object which is different than the TypeScript definition in my model property. While Typescript believe it is a buffer,,,,


### Link to sample repo to reproduce issue (if bug)



### Expected result



### Actual result (if bug)



### Additional information (Node.js version, LoopBack version, etc)

この issue は loopback-connector-sqlite3 と SQLite3 を挙げていますが、ファイル、テスト、再現用リポジトリについては何も言及していません。まず connector の型変換と取得の経路を特定し、次に Buffer プロパティの挙動を再現してください。保存された Buffer の値が JSON 形式の TEXT 値ではなく Buffer オブジェクトとして取得されれば、完了とします。