This permit to reduce the coupling between Pylinter and linterstats.
Also add two missing litteral in typing for module stats and independant
typing for ModuleStats attribute
Refactor prior to #4720
* Refactor ``self.stats`` on linter and checker
This adds a new class ``LinterStats`` which is used to store all
kinds of stats during a run of ``pylint``. Tests have been changed
slightly to be able to use the new class.
Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com>