refactor(models): abstractions of each image file

[hwakabh]

AsIs

Currently the images of each releases and thumbnails are implemented as static contents, but for allowing the site more dynamically, need to use express models to retrieve image path, or itselves.

ToDo

• [x] fix ORM solutions with TypeScript for Nest(Express)
• [x] add code bases of models, where we would define database schemas to use

(Optional) Acceptances

• [x] confirm we can use migration features provided by ORMs without any error
• [x] confirm database schemas will be applied to MySQL server on GCE instance

(Optional) Additional contexts

• The MySQL database to apply Nest(Express) models have been already provisioned as GCE instance in #68.
• The database on GCE instance is used and shared between several projects, which are also hosted on same GKE cluster as this application.

[hwakabh]

Following official documents related to database with Nest, we can notice that there is a lot of ORMs, which we can adopt. As noted in the document, it seems that major options of ORM with TypeScript are:

• TypeORM
• Prisma
• Sequelize

Considering we are using MySQL for backend database, whose tutorial is also noted in Nest documents with using TypeORM, we will adopt to use TypeORM as initial implementations.

[hwakabh]

confirm database schemas will be applied to MySQL server on GCE instance

We confirmed this with local MySQL container instead of GCE instances (Evidences), since the production GKE cluster is making error on cluster-side, so will mark as completed so far.