Rename @stytch/nextjs to @stytch/ssr

[alexandrutocar]

Hi, I could not find the source repo for @stytch/nextjs, that's why I write this issue here. In a nutshell, the name of the @stytch/nextjs package is confusing if used in a sever rendering environment which is not specifically nextjs, e.g. remix. Also, if you take into account the fact, that next is neither in the dev nor in peer - dependencies of the package, there is nothing really compelling about the naming choice for it. But people get really confused when they see a next package in a remix repo.