Revert breaking change in #126 (#128)

[IG-23065](https://iguazio.atlassian.net/browse/IG-23065)

Author: gtopper

v3io/dataplane/kv_array.py

@@ -39,7 +39,7 @@ def encode_array(array_value, typecode):
         "II" + typecode * num_items, num_items * 8, operand_type, *array_value
     )
 
-    return base64.b64encode(encoded_array).decode("utf-8")
+    return base64.b64encode(encoded_array)
 
 
 def decode(encoded_array):

v3io/dataplane/request.py

@@ -454,10 +454,10 @@ def _dict_to_typed_attributes(d):
             type_value = value
         elif isinstance(value, list):
             type_key = "B"
-            type_value = v3io.dataplane.kv_array.encode_list(value)
+            type_value = v3io.dataplane.kv_array.encode_list(value).decode("utf-8")
         elif isinstance(value, array.array):
             type_key = "B"
-            type_value = v3io.dataplane.kv_array.encode_array(value, value.typecode)
+            type_value = v3io.dataplane.kv_array.encode_array(value, value.typecode).decode("utf-8")
         elif isinstance(value, datetime.datetime):
             type_key = "TS"
             type_value = v3io.dataplane.kv_timestamp.encode(value)