include a script into datagouv

[vinyll]

When passing some query param on datagouv it should active the new search feature

Steps to achieve:

• [ ] make a PR on datagouv to include the external script
• [ ] create the external script in order to alter the home page

Note: check if it feels ok to call an external script that is not gouv.fr or should we create a subdomain?

[vinyll]

pr open at https://github.com/etalab/udata-gouvfr/pull/466

[vinyll]

integrated! 🎉