Provide a preview link of issues

[meness]

Provide a preview link to see the issues on the website.

It's configurable in the config file, e.g.:

{
  // Preview feature is disabled by default
  "preview": {
    "enable": true,
    "protected": true,
    "language": "Persian"
  }
}

[meness]

@ScreenTechnicals I think this isn't a good idea to add a preview feature. It doesn't make sense to me anymore

[meness]

@ScreenTechnicals Since we're going to add email integration, having a preview link doesn't make sense anymore