Add fields and tooling to support sub companies.
The new fields are
* `parent_ids`, which consists of all the ancestors of the current
company
* `root_id`, the upmost parent, which is the company controlling the
subsidiaries
* `parent_path` is added to avoid a hit on the performances when using
the multibranch feature
Also add a mechanism to ensure some fields are shared with a root
company and all it's descendents.
All fields listed by `_get_company_root_delegated_field_names` will be
readonly and copied from the `root_id`.
task-3371677
Part-of: odoo/odoo#125642
william-andre
dc4dcead6e