Support plaintext HTTP2 in HTTP server

[stratself]

Not sure if issue trackers do feature requests so here we go.

Currently, httpd doesn't support serving over HTTP/2 plaintext (h2c). A Caddyfile as below:

https://sftpgo.example.com {
    reverse_proxy {
        to  h2c://sftpgo:8080
    }
}

Will result in a 502. To amend, the line to h2c://sftpgo:8080 must be changed to to http://sftpgo:8080

Could there be a change to serve the web server with h2c and with only h2c? Inspiration is taken from here

Thanks in advance