Use custom findPagesDir function

[remorses]

findPagesDir in latest next returns an object instead of a path and will probably continue to break in the future, i vendored it in the code

Fix #38

[Janpot]

But vendoring is not going to help keep its behavior in sync with Next.js versions. Wouldn't it be better to keep importing and just checking whether it returns a string or not?

[remorses]

they don’t apply semver to it so it will break again when they change it

Also, If they change how pages behave then they are changing the whole framework, I don’t think it is going to happen anytime soon

[Janpot]

👍 Ok, can be merged after the code style issues are resolved