SolidStart v2 separation (#1557)

* Separate SolidStart v2 routes and enable v2 sidebar

* Add SolidStart v2 documentation for routing, API routes, data fetching, data mutation, overview, and getting started

* Add SolidStart v2 documentation for new server functions, middleware, and HTTP handling components

* Add v2 SolidStart serialization page

* ci: apply automated fixes

* Move SolidStart v2 docs under SolidStart routes

* ci: apply automated fixes

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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Brenley Dueck <brenleydueck@gmail.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>