Add option to remove h3 from alpn parameter of HTTPS RR #257

We need to add a new setting to filter out h3 alpn from HTTPS records.

;; ANSWER SECTION:
adguard.com.		300	IN	HTTPS	1 . alpn="h3,h2" ipv4hint=104.16.93.52,104.16.94.52 ipv6hint=2606:4700::6810:5d34,2606:4700::6810:5e34

->

;; ANSWER SECTION:
adguard.com.		300	IN	HTTPS	1 . alpn="h2" ipv4hint=104.16.93.52,104.16.94.52 ipv6hint=2606:4700::6810:5d34,2606:4700::6810:5e34

1. Add a new setting block_h3_alpn
2. Add a new function in svcb.h to patch alpn parameter and its length. If there's no alpns left in alpn, remove whole alpn parameter from reply.
3. Use it in dns_forwarder when processing HTTPS replies