[APPS-1213][BLOCKED] Add https support

:koala: :no_entry: 

This PR adds https support for zat server

### Risks

This PR make zat server https only
Developers need to add exception for the SSL certificate used in zat server

### Major problem

Developers have to go to https://localhost:4567/app.js first
to add an exception for the certificate

Without the exception, the app won't be loaded and the developers won't see any error message other than app.js not loaded (if they check network in dev tools)

The only way to bypass the certificate issue (say we don't buy an authorized certificate, even if we do want to, does certificate for localhost exist?) is to use port 443 (and the developers will have to use `sudo`), and we don't want to do this.

### Reference

* [Jira](https://zendesk.atlassian.net/browse/APPS-1213)


/cc @zendesk/quokka