curl's Experimental HTTPS RR Support: The Next Generation of DNS Records

curl now experimentally supports the new DNS record type HTTPS RR, offering a more modern way than SRV and URI to convey service metadata such as ECH configuration, ALPN lists, target hostnames, ports, and IP addresses. HTTPS RR enhances HTTPS connection security (via ECH encryption of the SNI field) and efficiency (by pre-fetching HTTP/3 support information), and simplifies service discovery. curl achieves HTTPS RR resolution through DoH, getaddrinfo(), or c-ares, but currently lacks runtime disabling and still has incomplete HTTPS RR support.