Implement MongoQueryableImpl ToCursor using 100% sync methods.

Author: rstam

src/MongoDB.Driver/Linq/MongoQueryProviderImpl.cs

@@ -105,7 +105,7 @@ public QueryableExecutionModel GetExecutionModel(Expression expression)
             return Translate(expression).Model;
         }
 
-        private object ExecuteModel(QueryableExecutionModel model)
+        internal object ExecuteModel(QueryableExecutionModel model)
         {
             return model.Execute(_collection, _options);
         }

src/MongoDB.Driver/Linq/MongoQueryableImpl.cs

@@ -73,7 +73,9 @@ public QueryableExecutionModel GetExecutionModel()
 
         public IAsyncCursor<TOutput> ToCursor(CancellationToken cancellationToken)
         {
-            return _queryProvider.ExecuteAsync<IAsyncCursor<TOutput>>(_expression, cancellationToken).GetAwaiter().GetResult();
+            var model = _queryProvider.GetExecutionModel(_expression);
+            var mongoQueryProvider = (MongoQueryProviderImpl<TInput>)_queryProvider;
+            return (IAsyncCursor<TOutput>)mongoQueryProvider.ExecuteModel(model);
         }
 
         public Task<IAsyncCursor<TOutput>> ToCursorAsync(CancellationToken cancellationToken)