Provide a more explicit error when import odoo fails

[sbidoul]

At

manifestoo/src/manifestoo/addons_path.py

Line 68 in d24b42b

echo.notice(f"could not obtain odoo.addons.__path__ using {python}")

, all we get when import odoo fails is could not obtain odoo.addons.__path__ using python.

When Odoo is not installed correctly, this may mask the root cause.

See for instance: OCA/l10n-spain#3733 (comment)

Investigate how a better error message could be provided, and in which circumstances exactly.

Related: #4