[IMP] sm modules: "neutralise" genders

Purpose
=======
Change all masculine nouns in Odoo's code to neutral nouns (when
possible), making sure that demo data is correctly handled. This is
particularly important since our code is open source, and nowadays lots
of machine learning models are trained on open source repositories.

With this small change we contribute to training more "fair" models, and
teaching models that "employee" or "user" != "he".

This also affects some text visible by the user, hence making it more
inclusive for Odoo users.

Task-2853046

closes odoo/odoo#91292

Related: odoo/enterprise#27302
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/knowledge/tests/test_knowledge_security.py

@@ -173,7 +173,7 @@ class TestKnowledgeSecurity(KnowledgeArticlePermissionsCase):
             self.article_roots.article_member_ids,
             'Members: employee should memberships of visible '
         )
-        # remove employee from Shared root, check he cannot read those members
+        # remove employee from Shared root, check they cannot read those members
         self.article_roots[2].article_member_ids.filtered(lambda m: m.partner_id == self.partner_employee).unlink()
         my_members = self.env['knowledge.article.member'].search([('article_id', 'in', self.article_roots.ids)])
         self.assertEqual(len(my_members), 2)