Pull request: all: fix lint and naming issues vol. 2

Merge in DNS/adguard-home from 2276-fix-lint-2 to master

Updates #2276.

Squashed commit of the following:

commit 24760b9586bb31be134ef9518dbece485560b1a0
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 7 14:39:50 2020 +0300

    all: fix lint and naming issues vol. 2

internal/dhcpd/v46_windows.go

@@ -1,11 +1,12 @@
+// +build windows
+
 package dhcpd
 
 // 'u-root/u-root' package, a dependency of 'insomniacslk/dhcp' package, doesn't build on Windows
 
 import "net"
 
-type winServer struct {
-}
+type winServer struct{}
 
 func (s *winServer) ResetLeases(leases []*Lease)            {}
 func (s *winServer) GetLeases(flags int) []Lease            { return nil }