Allow model to provide default values for auto creation of related res_partner
such as name, title, company_id, ...
It is used when claling 'Partner._find_or_create_from_emails()' that now
accepts custom data when creating partners based on a given email_normalized.
This allows notably to flatten a loop due to multi-company when creating
partners from emails in template management. It is now done using this email
based dict allowing to create all partners at once.
Task-3024050
Part-of: odoo/odoo#105111
Pierre-Yves Dufays
1018c72571