Extend linter rules (#1300)

- dupword checks for duplicate words in the source code
- durationcheck checks for two durations multiplied together
- forbidigo forbids identifiers
- mirror reports wrong mirror patterns of bytes/strings usage
- misspell finds commonly misspelled English words in comments
- predeclared finds code that shadows one of Go's predeclared identifiers
- thelper detects Go test helpers without t.Helper() call and checks the consistency of test helpers

client/internal/dns/server_test.go

@@ -771,6 +771,7 @@ func TestDNSPermanent_matchOnly(t *testing.T) {
 }
 
 func createWgInterfaceWithBind(t *testing.T) (*iface.WGIface, error) {
+	t.Helper()
 	ov := os.Getenv("NB_WG_KERNEL_DISABLED")
 	defer os.Setenv("NB_WG_KERNEL_DISABLED", ov)