Issue search support elasticsearch (#9428)

* Issue search support elasticsearch

* Fix lint

* Add indexer name on app.ini

* add a warnning on SearchIssuesByKeyword

* improve code

vendor/github.com/mailru/easyjson/raw.go

@@ -0,0 +1,45 @@
+package easyjson
+
+import (
+	"github.com/mailru/easyjson/jlexer"
+	"github.com/mailru/easyjson/jwriter"
+)
+
+// RawMessage is a raw piece of JSON (number, string, bool, object, array or
+// null) that is extracted without parsing and output as is during marshaling.
+type RawMessage []byte
+
+// MarshalEasyJSON does JSON marshaling using easyjson interface.
+func (v *RawMessage) MarshalEasyJSON(w *jwriter.Writer) {
+	if len(*v) == 0 {
+		w.RawString("null")
+	} else {
+		w.Raw(*v, nil)
+	}
+}
+
+// UnmarshalEasyJSON does JSON unmarshaling using easyjson interface.
+func (v *RawMessage) UnmarshalEasyJSON(l *jlexer.Lexer) {
+	*v = RawMessage(l.Raw())
+}
+
+// UnmarshalJSON implements encoding/json.Unmarshaler interface.
+func (v *RawMessage) UnmarshalJSON(data []byte) error {
+	*v = data
+	return nil
+}
+
+var nullBytes = []byte("null")
+
+// MarshalJSON implements encoding/json.Marshaler interface.
+func (v RawMessage) MarshalJSON() ([]byte, error) {
+	if len(v) == 0 {
+		return nullBytes, nil
+	}
+	return v, nil
+}
+
+// IsDefined is required for integration with omitempty easyjson logic.
+func (v *RawMessage) IsDefined() bool {
+	return len(*v) > 0
+}