fix(next-eslint): `.eslintrc.json` not being created by `next lint` on App Router (#55104)
This PR fixes `.eslintrc.json` not being created after the user runs
`next lint` and selects an option of `Strict` or `Base`.
The reason is that the lint check was looking for `pages` and
`src/pages` only. Added `app` and `src/app` to be checked also.
Fixes: #55094
Fixes: #55102
---------
Co-authored-by: JJ Kasper <jj@jjsweb.site>