Support Next.js pages router naming case for file name

[Nirajn2311]

Currently folder names are checked with the NEXT_JS_APP_ROUTER_CASE value to be in line with Next.js app routers naming conventions. Similarly can it also be added to the file naming convention rule as those also need to be inline with the same naming Next.js conventions but for pages router

[dukeluo]

I think KEBAB_CASE can do these things you said for files in nextjs app router project, so i havent add a new naming convention for the rule filename-naming-convention.

[Nirajn2311]

My bad, I was thinking of the pages router and got them muddled up when creating the issue.