Pull request: all: fix lint and naming issues vol. 3

Merge in DNS/adguard-home from 2276-fix-lint-3 to master

Updates #2276.

Squashed commit of the following:

commit 6ee94cc6ed2a9762b70ef395b58b496434244b80
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Dec 7 15:55:45 2020 +0300

    all: fix lint and naming issues vol. 3

internal/home/home_test.go

@@ -119,7 +119,7 @@ func TestHome(t *testing.T) {
 	fn := filepath.Join(dir, "AdGuardHome.yaml")
 
 	// Prepare the test config
-	assert.True(t, ioutil.WriteFile(fn, []byte(yamlConf), 0644) == nil)
+	assert.True(t, ioutil.WriteFile(fn, []byte(yamlConf), 0o644) == nil)
 	fn, _ = filepath.Abs(fn)
 
 	config = configuration{} // the global variable is dirty because of the previous tests run