Enable plot_config to work in webserver mode

(requires strategy argument)

freqtrade/rpc/rpc.py

@@ -1157,6 +1157,16 @@ class RPC:
             self._freqtrade.strategy.plot_config['subplots'] = {}
         return self._freqtrade.strategy.plot_config
 
+    @staticmethod
+    def _rpc_plot_config_with_strategy(config: Config) -> Dict[str, Any]:
+
+        from freqtrade.resolvers.strategy_resolver import StrategyResolver
+        strategy = StrategyResolver.load_strategy(config)
+
+        if (strategy.plot_config and 'subplots' not in strategy.plot_config):
+            strategy.plot_config['subplots'] = {}
+        return strategy.plot_config
+
     @staticmethod
     def _rpc_sysinfo() -> Dict[str, Any]:
         return {