Until now it was disabled which means that if Component A imports Component B
and the latter is not in {validated,modified} state, Component A could be
validated without raising any error and failed at execution time.

As this relies on Pylint transform/hook and avoiding monkey patch as much
as possible, make Products.ERP5Type.patches.pylint available for Python3 (not
actually tested with ERP5 but no AttributeError nor ImportError with Python3
with this code).

Also, allow developer to call validate action from 'modified' state to handle
import use case:
  1. Edit A which raises an error stating that B.
  2. Fix B and validate it.
  3. Validate again A without requiring a modification of {reference,version,text_content}.