v5: keepPreviousData codemod

[TkDodo]

• for feature: Combine keepPreviousData with placeholderData  #4688

keepPreviousData: true

should become:

placeholderData: (previousData) => previousData

OR, alternatively:

import { keepPreviousData } from '@tanstack/react-query'

placeholderData: keepPreviousData

If a placeholderData was already specified, it's fine if the codemod doesn't do anything and prints a warning instead. I think this case must be reviewed manually anyways.