Pull request: * all: move internal Go packages to internal/

Merge in DNS/adguard-home from 2234-move-to-internal to master

Squashed commit of the following:

commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 12:44:18 2020 +0300

    * all: move internal Go packages to internal/

    Closes #2234.

internal/home/rdns_test.go

@@ -0,0 +1,21 @@
+package home
+
+import (
+	"testing"
+
+	"github.com/AdguardTeam/AdGuardHome/internal/dnsforward"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestResolveRDNS(t *testing.T) {
+	dns := &dnsforward.Server{}
+	conf := &dnsforward.ServerConfig{}
+	conf.UpstreamDNS = []string{"8.8.8.8"}
+	err := dns.Prepare(conf)
+	assert.True(t, err == nil, "%s", err)
+
+	clients := &clientsContainer{}
+	rdns := InitRDNS(dns, clients)
+	r := rdns.resolve("1.1.1.1")
+	assert.True(t, r == "one.one.one.one", "%s", r)
+}