Alias for Allowed fields different from the ones in the database

[Mina-R-Meshriky]

Currently v5, when we set the allowed fields, we need to set them as they appear in the database schema
It will be very nice to have something like this:

->allowedFields([ 
'createdAt' => 'created_at'
])

Since, in the resource file we already send all keys with camelcase, and sometimes the field name in the database is completely different than the field sent in the resource response.

This way the frontend dev. can work with only one set of keys.