New methods S3 client

Signed-off-by: Dmitriy Zayakin <d.zayakin@yadro.com>

src/frostfs_testlib/s3/interfaces.py

@@ -34,6 +34,10 @@ class S3ClientWrapper(ABC):
     def __init__(self, access_key_id: str, secret_access_key: str, s3gate_endpoint: str) -> None:
         pass
 
+    @abstractmethod
+    def set_endpoint(self, s3gate_endpoint: str):
+        """Set endpoint"""
+
     @abstractmethod
     def create_bucket(
         self,