[Upstream] Mobile Content Service issues

[jdlrobson]

I want to upstream all the work done in libs/server/endpoints/page.js and use rest directly to power weekipedia.

Open bugs

• Invalidation of current page after an edit - https://phabricator.wikimedia.org/T156842

Resolved upstream in new MCS endpoint (not yet deployed)

• Hatnotes: https://phabricator.wikimedia.org/T143739
• Page Issues: https://phabricator.wikimedia.org/T143740
• Coordinates: https://phabricator.wikimedia.org/T145003
• Duplicate info: https://phabricator.wikimedia.org/T145006
• IPA content: https://phabricator.wikimedia.org/T141835
• Handling of file and user pages (https://phabricator.wikimedia.org/T148118)

[jdlrobson]

All bugs are fixed except https://phabricator.wikimedia.org/T141835