Pull request: Migrate to netip.Addr vol.1

Merge in DNS/adguard-home from 2926-lla-v6 to master

Updates #2926.
Updates #5035.

Squashed commit of the following:

commit 2e770d4b6d4e1ec3f7762f2f2466662983bf146c
Merge: 25c1afc5 893358ea
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Oct 14 15:14:56 2022 +0300

    Merge branch 'master' into 2926-lla-v6

commit 25c1afc5f0a5027fafac9dee77618886aefee29c
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Oct 13 18:24:20 2022 +0300

    all: imp code, docs

commit 59549c4f74ee17b10eae542d1f1828d4e59894c9
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Oct 11 18:49:09 2022 +0300

    dhcpd: use netip initially

commit 1af623096b0517d07752385540f2f750f7f5b3bb
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Fri Sep 30 18:03:52 2022 +0300

    all: imp docs, code

commit e9faeb71dbc0e887b25a7f3d5b33a401805f2ae7
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Thu Sep 29 14:56:37 2022 +0300

    all: use netip for web

commit 38305e555a6884c3bd1b0839330b942ce0e59093
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Sep 28 19:13:58 2022 +0300

    add basic lla

internal/dnsforward/access.go

@@ -19,6 +19,7 @@ import (
 // accessCtx controls IP and client blocking that takes place before all other
 // processing.  An accessCtx is safe for concurrent use.
 type accessCtx struct {
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	allowedIPs *netutil.IPMap
 	blockedIPs *netutil.IPMap
 

internal/dnsforward/dnsforward.go

@@ -81,6 +81,7 @@ type Server struct {
 	tableHostToIP     hostToIPTable
 	tableHostToIPLock sync.Mutex
 
+	// TODO(e.burkov):  Use map[netip.Addr]struct{} instead.
 	tableIPToHost     *netutil.IPMap
 	tableIPToHostLock sync.Mutex