chore: App Router - remove references to `/pages` for remaining pages in `/auth`, `/insights`, `/d`, `signup` and add missing default `/future` page (#16589)

* remove references to /pages for sso, setup, signin pages in /auth

* remove references to pages for insights

* remove references to pages for d

* remove references to pages for signup

* add page for /future index page

* fix routing-forms

* fix

* add missing defaults

* use getServerSessionForAppDir instead

* fix apps/[slug]/[...pages]

* fix metadata in apps/slug/pages

* refactor

* refactor

* remove duplicate code for PageProps

* remove references to pages for /reschedule

* fix

* fix routing forms

* type fix

* fix routing forms again

* revert changes for app/slug/pages

* revert

* revert changes in yarn lock

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Co-authored-by: Joe Au-Yeung <65426560+joeauyeung@users.noreply.github.com>