Added low-level support for HTTPS and UPnP

[eltsai]

Added two new low-level emulation: HTTPS and UPnP:

HTTPS service (using the same template as HTTP):

Because we are using a self-signed certicate, major browsers will mark the connection as insecure (ERR_CERT_AUTHORITY_INVALID):

Future users can register their own domain and use services like Let's Encrypt or Cloudflare to get a certificate trusted by most root stores.

For UPnP, I implemented it to respond to a M-POST request:

$ curl -i -X M-POST -H "SOAPAction: GetExternalIPAddress" http://localhost:1900/
HTTP/1.1 200 OK
Content-Type: text/xml
Date: Wed, 28 Jun 2023 05:32:40 GMT
Content-Length: 339

            <?xml version="1.0"?>
            <s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
                <s:Body>
                    <u:GetExternalIPAddressResponse xmlns:u="urn:schemas-upnp-org:service:WANIPConnection:1">
                        <NewExternalIPAddress>192.168.1.100</NewExternalIPAddress>
                    </u:GetExternalIPAddressResponse>
                </s:Body>
            </s:Envelope>

[eltsai]

Added test cases for low-level HTTPS and UPNP server emulation:

1. HTTPS: testing status code, HTTP content and TLS content
2. UPNP: testing status code and response to M-POST

   
   ~/riotpot/test/internal/plugins$ go test upnpd_test.go 
   ok      command-line-arguments  0.012s
   ~/riotpot/test/internal/plugins$ go test httpsd_test.go 
   ok      command-line-arguments  0.023s