Configurable date format separator

Can't change date format separator.

In current version of GLPI (9.3.3) it is not able to change date format to custom settings (Setup - General - Default values: Date format, or profile - Personalization - Date format). There is only selection of date format from only 3 options:

1. YYYY-MM-DD
2. DD-MM-YYYY
3. MM-DD-YYYY

Problem is especially with separator - (dash) which is not configurable. For example in Slovak/Czech language we use . (dot) as a separator for date and not dash:
29.11.2018

Another languages use / as separator etc.

So it would be great to have option to also change separator for date format.

Describe the solution you'd like

Please add option to change separator for date format. Or better to able to also use custom php format:
http://php.net/manual/en/function.date.php.

For example Wordpress uses 4 predefined options a you can also use your own custom which is great:
https://www.wpbeginner.com/beginners-guide/how-to-change-date-and-time-format-in-wordpress/