Save strategies as part of the backtest report

[MDUYN]

``During backtesting there should be an option to save the strategy as part of the backtest.

This should look like this for in memory strategies

app = create_app()
end_date = datetime(2023, 12, 2)
start_date = end_date - timedelta(days=100)
date_range = BacktestDateRange(
    start_date=start_date,
    end_date=end_date
)
backtest_report = app.run_backtest(
      backtest_date_range=date_range, save_strategy=True
)

and for a strategies directory:

app = create_app()
end_date = datetime(2023, 12, 2)
start_date = end_date - timedelta(days=100)
date_range = BacktestDateRange(
    start_date=start_date,
    end_date=end_date
)
backtest_report = app.run_backtest(
      backtest_date_range=date_range, save_strategies_directory=True
)
# or
backtest_report = app.run_backtest(
      backtest_date_range=date_range, save_strategies_directory=True, strategies_directory_name=""
)