Set order from sort_parameters as fallback

[franmomu]

Subject

This was triggered investigating the warnings triggered by PHP 8.1: https://github.com/sonata-project/SonataAdminBundle/pull/7528/checks?check_run_id=3837943478#step:10:53

The problem is that when doing {{ sort_by|lower }}, sort_by is null in our tests.

This PR will partially fix it (I'll make another one in 4.x removing our implementation in tests of DatagridInterface and using the one from the bundle).

What it does it to set the order from sort_parameters if it is not defined in the field description.

I am targeting this branch, because this is a bugfix.

Changelog

### Fixed
- Fixed setting a default order if it is not set in the field description

[VincentLanglet]

I'm not sure to understand the issue ; do we have a way to reproduce it in the tests ?

[franmomu]

The issue is about to provide a default value for sort_by in case it is not set in the field description, I saw it when using

SonataAdminBundle/tests/App/Admin/FooAdmin.php

Lines 38 to 41 in b3815f2

	$list
	->add('name', FieldDescriptionInterface::TYPE_STRING, [
	'sortable' => true,
	])

where sort_by is null in

SonataAdminBundle/src/Resources/views/CRUD/base_list.html.twig

Line 76 in ec8c8ab

{% set sort_by = current ? admin.datagrid.values[constant('Sonata\\AdminBundle\\Datagrid\\DatagridInterface::SORT_ORDER')] : field_description.option(constant('Sonata\\AdminBundle\\Datagrid\\DatagridInterface::SORT_ORDER')) %}

with this change sort_by will be ASC since it's the default value from sort_parameters.

It's in twig, so I don't think there is an easy way to test this.