To support progress in T225213 which will improve the main menu experience for all users (including non-js users) and to remove maintenance burden (Special:MobileMenu) we should server side render the MainMenu in Minerva.
This will enable us to apply a CSS only solution meaning users will never land on the Special:MobileMenu page again.
= Acceptance criteria
[x] The menu is server side rendered
[] The MainMenu inside Minerva no longer makes use of MobileFrontend's View.
[] Menu templates are moved into the includes folder.
= Developer notes
Cached HTML is an issue. We will need to do this task in 2 chunks
[x] Server side render the contents of the main menu (DONE)
[x] Wait 2 weeks (from 8th October)
[] Remove the client side rendering
= QA steps
[] Verify there are no consequences on cached HTML.
[] Verify that a view source shows the menu HTML on non-cached HTML.