With input 'name email@domain.com' (missing chevrons allowing to clearly spot
the email part) 'getaddresses' returns ('', 'name email@domain.com) i.e. the
whole input is considered as being the email.

To improve the heuristic we can add a fallback by recalling 'getadresses'
on the input with spaces replaced by commas when it found only an email and
no name. The new email will be split into sub pairs allowing to find the real
email and various name parts, allowing to make a new name / email pair.

Emails should not contain spaces thus this is coherent with email formation.
This fallback actually comes from a specific code done in '_parse_partner_name'
of Partner model. Supporting it directly at tools level make the behavior
coherent for all models.

Task-2612945 (Mail: Defensive email formatting)

X-original-commit: odoo/odoo@b2f3f0f3e13cef993541bcd093e61ffbb6a8c92e
Part-of: odoo/odoo#133958