✨(frontend) update doc header ui

Modification of the header style to be consistent with the new UI :
- We replace the option menu with the DropdownMenu component
- We add a dowload button
- We put an input in place of an editable div.

CHANGELOG.md

@@ -89,6 +89,7 @@ and this project adheres to
 - ✨(frontend) add sentry #424
 - ✨(frontend) add crisp chatbot #450
 - 💄(frontend) update DocsGridOptions component #432
+- 💄(frontend) update DocHeader ui #446
 
 
 ## Changed