Traceback generated when trying to pass a datetime object into a function tag
in xml.

<function name="action_name" model="model_name" eval="datetime.date.today"/>

Used to fail.

With this commit now one can pass time, datetime, timedelta, relativedelta,
version, ref, pytz in function tag in xml

Task-id: 1772614
Closes odoo/odoo#29212

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>


Co-authored-by: Dhaval Limbuwala <dli@odoo.com>

closes odoo/odoo#31417

Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

* add tests for uid/context on record & function & root nodes (odoo,
  data, openerp) "inherited" by record & function
* add rng validation to the test cases to ensure technical
  capabilities are matched by validation capabilities (which was not
  the case as we could validate nonsense and import stuff which didn't
  pass validation or something)
* extact uid/context into its own rng pattern
  - add uid support to record validation
  - add uid support to root nodes validation
  - fix uid support on function validation: was typoed to @id, which
    is not used anywhere in function tags loading & makes no sense
    as far as I can tell
* replace get_uid/get_context by get_env & reimplement the whole mess:
  build a stack of environments from the root nodes (each root node =
  one env in the stack, though the exact same env can be present
  multiple times if none of the root nodes has a @uid or @context) and
  leaves can build upon this "ready made" environment for their own
  uses or use it as-is.

  As a result, all uid/context should now properly transfer from the
  root nodes to the leaves needing them
* fix support for context on functions: was not actually implemented
  as the context was not propagated into the old-style API call
* add uid support to record & context is now inherited from env