feat(cli): improve scaffolding of complex model settings

[bajtos]

Leverage stringify-object package to convert model settings object into well-formatted TypeScript source code.

An example of a simple settings object:

@model({settings: {strict: false}})
export class MyModel extends Entity {
  // ...
}

A more complex example:

@model({
  settings: {
    annotations: [{destinationClass: 'class1', argument: 0}],
    foreignKeys: {fk_destination: {name: 'fk_destination'}},
    strict: false
  }
})
export class MyModel extends Entity {
  // ...
}

See #2604 /cc @yanamg7

Checklist

👉 Read and sign the CLA (Contributor License Agreement) 👈

• npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

👉 Check out how to submit a PR 👈

[nabdelgadir]

Thanks for improving this 💯