Adjust rolling api (#1594)

* Intermediate version

* Fix yaml template & Successfully run rolling

* Be compatible with benchmark

* Get same results with previous linear model

* Black formatting

* Update black

* Update the placeholder mechanism

* Update CI

* Update CI

* Upgrade Black

* Fix CI and simplify code

* Fix CI

* Move the data processing caching mechanism into utils.

* Adjusting DDG-DA

* Organize import

qlib/backtest/__init__.py

@@ -182,7 +182,6 @@ def get_strategy_executor(
     exchange_kwargs: dict = {},
     pos_type: str = "Position",
 ) -> Tuple[BaseStrategy, BaseExecutor]:
-
     # NOTE:
     # - for avoiding recursive import
     # - typing annotations is not reliable

qlib/backtest/exchange.py

@@ -638,7 +638,6 @@ class Exchange:
         random.seed(0)
         random.shuffle(sorted_ids)
         for stock_id in sorted_ids:
-
             # Do not generate order for the non-tradable stocks
             if not self.is_stock_tradable(stock_id=stock_id, start_time=start_time, end_time=end_time):
                 continue