fix maps.Thumbnail

Remove fields from MapResponse and other structs that will not be used in embedded contexts.

Reviewed-on: #5
Co-authored-by: Rhys Lloyd <krakow20@gmail.com>
Co-committed-by: Rhys Lloyd <krakow20@gmail.com>

maps.proto

@@ -24,22 +24,19 @@ message IdMessage {
 message MapResponse {
   int64 ID = 1;
   string DisplayName = 2;
-  string Creator = 3;
   int32 GameID = 4;
-  int64 Date = 5;
+  uint64 Thumbnail = 6;
 }
 
 message MapRequest {
   int64 ID = 1;
   optional string DisplayName = 2;
-  optional string Creator = 3;
   optional int32 GameID = 4;
-  optional int64 Date = 5;
+  optional uint64 Thumbnail = 6;
 }
 
 message MapFilter {
   optional string DisplayName = 2;
-  optional string Creator = 3;
   optional int32 GameID = 4;
 }
 
@@ -58,5 +55,4 @@ message Pagination {
 }
 
 message NullResponse {
-
-}
+}