Parameter: correct .set post-initialization check (#3116)

Parameter.set checks for Component values assigned after
its owning Component's __init__ so that the assigned Components
can be shaped compatibly and set up for later context initialization.

Check for ContextFlags.INITIALIZED initialization_status instead of
is_initialized, because is_initialized also considers any initialization
context, not just the status of having completed Component.__init__

psyneulink/core/globals/parameters.py

@@ -1516,7 +1516,7 @@ def set(self, value, context=None, override=False, skip_history=False, skip_log=
         if isinstance(value, Component):
             owner = self._owner._owner
             if value not in owner._parameter_components:
-                if not owner.is_initializing:
+                if owner.initialization_status == ContextFlags.INITIALIZED:
                     value._initialize_from_context(context)
                     owner._parameter_components.add(value)