Consider converting to plugin

[rohit-gohri]

Objection.js Plugins: https://vincit.github.io/objection.js/guide/plugins.html
https://vincit.github.io/objection.js/guide/plugins.html#plugin-development-best-practices

We could break the Model class into multiple simpler plugins:

• Cache/Redis-Cache
• Data-Loader
• Soft Delete
• Timestamps
• Query building helpers
• GraphQL helpers

By default xorm could export objection with all plugins applied, while also exporting individual plugins allowing one to use only those features they need