Update experimental-https flags to support wildcard certificates

[CopyJosh]

Goals

1. Support https over subdomains on a local development server out of the box

Non-Goals

1. Support complex domain certificates that a user can create and import using additional configuration

Background

Consider the Platform Starter Kit as an example, but any multi-tenant or application that serves content over multiple subdomains on a single instance would benefit from out of the box support for https in local development. That requires generating certificates to support subdomains.

Proposal

Since the --experimental-https is still experimental, I think this is a good opportunity to discuss what an API would look like for supporting wildcard subdomains. These are the existing flags from the API Reference:

--experimental-https                     Starts the server with HTTPS and generates a self-signed certificate.
  --experimental-https-key, <path>         Path to a HTTPS key file.
  --experimental-https-cert, <path>        Path to a HTTPS certificate file.
  --experimental-https-ca, <path>          Path to a HTTPS certificate authority file.

I created a repo with a new flag --experimental-https-wildcard and updated API of the createSelfSignedCertificate function.

Run as: next dev --experimental-https --experimental-https-wildcard

https://github.com/CopyJosh/next-dev-create-wildcard-certificates/tree/experimental-https-wildcard-flag

Alternatively I thought about allowing the existing flag to accept a parameter --experimental-https wildcard or keeping the existing flag simple and enforcing the details through the next.config.js.

Overall I think this feature would benefit from having this functionality.

Thanks

PS. Realize I may be duplicating #33768 which generally discusses https support.