Sets by default the long date format on the date picker form type

[DavidHernandez]

Subject

Sets by default the long date format to allow forms in Spanish to submit dates without extra configuration.

Branch

I'm targeting this branch because it fixes a small issue that affects only sites with a Spanish locale and using the DatePicker form type when using the default or medium DateType Format. This change will not break any existing site but it will change the format used in the form fields that are not directly changed to use a different format.

Issue

The issue being resolved was originally reported on the SonataAdminBundle: https://github.com/sonata-project/SonataAdminBundle/issues/5235

Changelog

Changed

• Changes the default DateType format on the DatePicker form type to prevent errors when using Spanish locale.

[OskarStark]

Can you please share a before/after screenshot?

[core23]

After merging this, please open an other PR here: https://github.com/sonata-project/form-extensions

The CoreBundle is deprecated

[DavidHernandez]

The before Medium format:

It causes an error on save:

After changing the format:

It works properly:

[core23]

Does this affect the English date format?

[OskarStark]

I would say yes

[core23]

Did the format change for the English locale?

[jordisala1991]

This change should be applied on form-extension package