[REF] website*: revamp res_config_settings for website

Reorder res.config.settings for website
Make website_id in no create in most view
Revamp res.configsetting and view Form simplified

Transform old 'useless' stored field for presentation by computed field.
We can consider that if there are not key, feature is disable.

Co-authored-by: rde-odoo
Co-authored-by: jke-odoo