Plugin dnstap: add support for "extra" field in payload (#6226)

* dnstap: add 'extra' field

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: add setup_test for 'extra' field

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* udnstap: update document and test

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: update setup_test for more coverage

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: add TapMessageWithMetadata function to Dnstap

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: adapt dnstap and forward plugins to use TapMessageWithMetadata

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* change TapMessageWithMetadata function

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* tab inconsistency fix

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* fix replacer to support empty state

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* add replacer test for empty status parameter

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: update unit test for 'extra' field

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* clean up code

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* gofmt fix & static analysis fix

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

* dnstap: refactor

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

---------

Signed-off-by: chenyuheng <chenyuheng99@qq.com>

plugin/pkg/replacer/replacer_test.go

@@ -256,6 +256,12 @@ func TestLabels(t *testing.T) {
 		if repl != expect[lbl] {
 			t.Errorf("Expected value %q, got %q", expect[lbl], repl)
 		}
+
+		// test empty state and nil recorder won't panic
+		repl_empty := replacer.Replace(ctx, request.Request{}, nil, lbl)
+		if repl_empty != EmptyValue {
+			t.Errorf("Expected empty value %q, got %q", EmptyValue, repl_empty)
+		}
 	}
 }