Mixed content warning / please serve generator.swagger.io via https by default

Description

generator.swagger.io is not served via https by default.
When I try to download a server from editor.swagger.io the download fails and my browser (chrome or firefox) send a warning to the console that the content is mixed, because editor.swagger.io is served via https and generator.swagger.io is not (by default).

That's because the swagger editor uses the following code to download the generated files:

this.downloadFile(res, `${name}-${type}-generated.zip`)

https://github.com/swagger-api/swagger-editor/blob/master/src/standalone/topbar/topbar.jsx#L180

downloadFile = (content, fileName) => {
  return reactFileDownload(content, fileName)
}

https://github.com/swagger-api/swagger-editor/blob/master/src/standalone/topbar/topbar.jsx#L44

Swagger-codegen version

2.4.0

Steps to reproduce

• Go to https://editor.swagger.io/
• Click "generate server" and try to download a server
• Have a look into your browsers console

Suggest a fix/enhancement

Serve generator.swagger.io via https (by default).

Start with the referenced src/standalone/topbar/topbar.jsx download flow, then locate the deployment or configuration for generator.swagger.io. The issue is done when generated server downloads from editor.swagger.io use HTTPS by default and no mixed-content warning occurs in Chrome or Firefox.