unified-storage: use name instead of offset in kvstore continue token (#113560)

* unified-storage: use name instead of offset in kvstore continue token

---------

Co-authored-by: Georges Chaudy <chaudyg@gmail.com>

pkg/storage/unified/sql/continue.go

@@ -0,0 +1,33 @@
+package sql
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+)
+
+type ContinueToken struct {
+	StartOffset     int64 `json:"o"`
+	ResourceVersion int64 `json:"v"`
+	SortAscending   bool  `json:"s"`
+}
+
+func (c ContinueToken) String() string {
+	b, _ := json.Marshal(c)
+	return base64.StdEncoding.EncodeToString(b)
+}
+
+func GetContinueToken(token string) (*ContinueToken, error) {
+	continueVal, err := base64.StdEncoding.DecodeString(token)
+	if err != nil {
+		return nil, fmt.Errorf("error decoding continue token")
+	}
+
+	t := &ContinueToken{}
+	err = json.Unmarshal(continueVal, t)
+	if err != nil {
+		return nil, err
+	}
+
+	return t, nil
+}