Refactor bot_start to separate function

to be reused further ...

freqtrade/optimize/edge_cli.py

@@ -44,7 +44,7 @@ class EdgeCli:
 
         self.edge._timerange = TimeRange.parse_timerange(None if self.config.get(
             'timerange') is None else str(self.config.get('timerange')))
-        self.strategy.bot_start()
+        self.strategy.ft_bot_start()
 
     def start(self) -> None:
         result = self.edge.calculate(self.config['exchange']['pair_whitelist'])