In this PR, behind a feature flag, we add a permission layer check based
on the read permission.
It is done by computing a map of an object's fields, where keys are the
column names and values the fieldMetadata id, making them comparable to
the restricted fields ids list stored in the permission cache.
For mutations (create, update, delete, destroy), we need to check the
read permission on the returned field, as they may differ from the
updated field. The write field permission will be tackled in a different
PR.
ae6adb3a63