[Python] Local imports in _facade.py to delay pythonization lib. loading

This should fix errors on Windows where the `libROOTPythonizations` is
attempted to be loaded before the DLL directory is set correctly in
`ROOT/__init__.py`.

Author: guitargeek

bindings/pyroot/pythonizations/python/ROOT/_facade.py

@@ -7,10 +7,6 @@
 import cppyy
 import cppyy.ll
 
-from ._application import PyROOTApplication
-from ._numbadeclare import _NumbaDeclareDecorator
-from ._pythonization import pythonization
-
 
 class PyROOTConfiguration(object):
     """Class for configuring PyROOT"""
@@ -57,6 +53,8 @@ class ROOTFacade(types.ModuleType):
     """Facade class for ROOT module"""
 
     def __init__(self, module, is_ipython):
+        from ._pythonization import pythonization
+
         types.ModuleType.__init__(self, module.__name__)
 
         self.module = module
@@ -181,6 +179,8 @@ def _register_converters_and_executors(self):
             CPyCppyyRegisterExecutorAlias(name, target)
 
     def _finalSetup(self):
+        from ._application import PyROOTApplication
+
         # Prevent this method from being re-entered through the gROOT wrapper
         self.__dict__["gROOT"] = cppyy.gbl.ROOT.GetROOT()
 
@@ -443,6 +443,8 @@ def TMVA(self):
     # Create and overload Numba namespace
     @property
     def Numba(self):
+        from ._numbadeclare import _NumbaDeclareDecorator
+
         cppyy.cppdef("namespace Numba {}")
         ns = self._fallback_getattr("Numba")
         ns.Declare = staticmethod(_NumbaDeclareDecorator)