[IMP] base, account: `refs` for multiple records retrieval

[lordkrandel]

The ref method both in Environment and in ChartTemplate can now accept multiple xml_ids, reducing the number of queries necessary. The xml_ids must all refer to the same model, or ValueError is raised. raise_if_not_found argument is made a keyword-only argument so now it's mandatory for the function calls to include the argument name.

Community PR: odoo/odoo#179692 Enterprise PR: odoo/enterprise#69800

[robodoo]

[william-andre]

This should have the same branch name as https://github.com/odoo/odoo/pull/179692 in order to be merged and tested together

[lordkrandel]

This should have the same branch name as odoo/odoo#179692 in order to be merged and tested together

The strange thing, it appears to me, is that they have.

[lordkrandel]

I just remembered I created it with the wrong target, then changed it straight after, probably it's unaligned. I'm asking the runbot team.