Refactor metaToJsonProperty to accept AJV keywords

[iqbaldjulfri]

Description

We need to add additional attributes (AJV keywords) from PropertyDefinition so they will be written to openapi.json and we can use it as validation. Currently, only type, description, items (for arrays), and $ref are written (and a hard-coded format: 'date-time' for Date instances).

Current Behavior

@model()
export class Employee extends Entity {
  @property({
    type: 'string',
    required: true,
    format: 'email', // this won't be written to openapi.json
  })
  email: string;

  @property({
    type: 'string',
    required: true,
    pattern: '(staff|manager|director)', // this also won't be written to openapi spec
  })
  type: string;
}

Expected Behavior

Other AJV keywords is written to openapi spec

[iqbaldjulfri]

#2685 this is the pull request for this issue

[dhmlau]

@iqbaldjulfri, let me assign this issue to you since you have a PR up.

[bajtos]

I feel this is a duplicate of #1624

[iqbaldjulfri]

the solution has been merged in #2685 .