add freqao backend machinery, user interface, documentation

freqtrade/freqai/strategy_bridge.py

@@ -0,0 +1,12 @@
+from freqtrade.resolvers.freqaimodel_resolver import FreqaiModelResolver
+
+
+class CustomModel:
+    """
+    A bridge between the user defined IFreqaiModel class 
+    and the strategy.
+    """
+
+    def __init__(self,config):
+
+        self.bridge = FreqaiModelResolver.load_freqaimodel(config)