Pull request: 2552 rm context.TODO() instances

Merge in DNS/adguard-home from 2552-context to master

Closes #2552.

Squashed commit of the following:

commit 3d1cef33da529f4611869c4a0f2f294a3c8afcaf
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 26 19:28:23 2021 +0300

    all: fix docs

commit d08c78cf4b96419b928e73c497768f40c9e47bc2
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 26 19:22:00 2021 +0300

    all: doc changes

commit c2814f4d0025be74f38299e7e66e7c0193b6c15f
Merge: 100a1a09 44c7221a
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 26 19:12:55 2021 +0300

    Merge branch 'master' into 2552-context

commit 100a1a0957bc22bfaccb1693e6b9b1c5cb53ed13
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 26 19:10:03 2021 +0300

    home: imp docs, fix naming

commit 22717abe6c0e4c1016a53ff2fac1689d0762c462
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue Jan 26 18:14:07 2021 +0300

    home: improve code quality

commit 5c96f77a2b315e2c1ad4a11cc7a64f61bdba52a3
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Jan 25 20:28:51 2021 +0300

    home: add docs

commit 323fc013a57a5c06ec391003133b12f4eb2721cd
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Mon Jan 25 14:50:11 2021 +0300

    home: rm context.TODO() instances

internal/home/whois_test.go

@@ -1,6 +1,7 @@
 package home
 
 import (
+	"context"
 	"testing"
 
 	"github.com/AdguardTeam/AdGuardHome/internal/dnsforward"
@@ -19,7 +20,7 @@ func TestWhois(t *testing.T) {
 	assert.Nil(t, prepareTestDNSServer())
 
 	w := Whois{timeoutMsec: 5000}
-	resp, err := w.queryAll("8.8.8.8")
+	resp, err := w.queryAll(context.Background(), "8.8.8.8")
 	assert.Nil(t, err)
 	m := whoisParse(resp)
 	assert.Equal(t, "Google LLC", m["orgname"])