PURPOSE Prepare sales team membership and lead assignment improvements by reorganizing and cleaning some code bits. SPECIFICATIONS Tools methods should be private by default to indicate those are not part of official convert or merge API for leads. In this commit we make convert and merge tool methods private, keeping only main API methods public. LINKS Task ID-2428882 Prepares Task ID-2086889 COM PR odoo/odoo#64196 ENT PT odoo/enterprise#15610