cherry-pick: 4542 clientid case

Merge in DNS/adguard-home from 4542-clientid-case to master

Updates #4542.

Squashed commit of the following:

commit 2a3111e
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed May 4 20:44:18 2022 +0300

    all: fix changelog link

commit 3732def
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed May 4 20:43:37 2022 +0300

    all: log changes

commit 9fe1001
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed May 4 19:37:33 2022 +0300

    dnsforward: lowercase clientid

internal/home/clients.go

@@ -530,7 +530,7 @@ func (clients *clientsContainer) check(c *Client) (err error) {
 		} else if mac, err = net.ParseMAC(id); err == nil {
 			c.IDs[i] = mac.String()
 		} else if err = dnsforward.ValidateClientID(id); err == nil {
-			c.IDs[i] = id
+			c.IDs[i] = strings.ToLower(id)
 		} else {
 			return fmt.Errorf("invalid clientid at index %d: %q", i, id)
 		}