Purpose
========
In expense, we now allow any simple employee (no sales access rights) to
select sales order. Technically, the name_search is done in sudo mode,
to allow simply fetching the name_get of record.
The problem is that the m2o field widget displays the "search more"
option and click on that will open a modal executing a "search_read"
which is causing access error as the user doesn't have read access on
SO.
As we want to restrict the visible information from the SO(only name_get)
to all user, we can't hack the search_read too.
Specification
=============
To prevent user frustration, we need to remove the "search more" option.
Thus, make a private function which one have 'search more..' option
related stuff and create a new widget for sale_expense, override that
function which one is returing values as it is without any modification.
task-2057714
closesodoo/odoo#36152
Signed-off-by: Jérome Maes (jem) <jem@openerp.com>