Python: Use more general definitions

This is a wip commit to see the effect

Author: yoff

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowPrivate.qll

@@ -299,6 +299,10 @@ module LocalFlow {
       nodeTo.(CfgNode).getNode() = def.getDefiningNode()
     )
     or
+    // General definition
+    // TODO: remove other cases that are now redundant
+    nodeFrom.(CfgNode).getNode() = nodeTo.(CfgNode).getNode().(DefinitionNode).getValue()
+    or
     // With definition
     //   `with f(42) as x:`
     //   nodeFrom is `f(42)`