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/routeradv_test.go

@@ -0,0 +1,31 @@
+package dhcpd
+
+import (
+	"bytes"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRA(t *testing.T) {
+	ra := icmpv6RA{
+		managedAddressConfiguration: false,
+		otherConfiguration:          true,
+		mtu:                         1500,
+		prefix:                      net.ParseIP("1234::"),
+		prefixLen:                   64,
+		recursiveDNSServer:          net.ParseIP("fe80::800:27ff:fe00:0"),
+		sourceLinkLayerAddress:      []byte{0x0a, 0x00, 0x27, 0x00, 0x00, 0x00},
+	}
+	data := createICMPv6RAPacket(ra)
+	dataCorrect := []byte{
+		0x86, 0x00, 0x00, 0x00, 0x40, 0x40, 0x07, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x03, 0x04, 0x40, 0xc0, 0x00, 0x00, 0x0e, 0x10, 0x00, 0x00, 0x0e, 0x10, 0x00, 0x00, 0x00, 0x00,
+		0x12, 0x34, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x05, 0x01, 0x00, 0x00, 0x00, 0x00, 0x05, 0xdc, 0x01, 0x01, 0x0a, 0x00, 0x27, 0x00, 0x00, 0x00,
+		0x19, 0x03, 0x00, 0x00, 0x00, 0x00, 0x0e, 0x10, 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x08, 0x00, 0x27, 0xff, 0xfe, 0x00, 0x00, 0x00,
+	}
+	assert.True(t, bytes.Equal(data, dataCorrect))
+}