- fold DoH and async HTTPS-RR handling into common code.
have common cleanups, etc. Have a CURLcode result in async
handling to allow HTTPS RR parsing to fail.
- keep target, ipv4hints, ipv6hints, port and echconfig also
when resolving via cares. We need to know `target` and `port`
when evaluating possible ALPN candidates to not go astray.
- add CURL_TRC_DNS for tracing DNS operations
- replace DoH specific tracing with DNS, use doh as alias
for dns in curl_global_tracea()
Closes#16132
1b710381ca