Add support for applying extra ACL

Why it matters

This feature allows administrators to impose extra access control restrictions on selected nodes within the Keeper service hierarchy, enabling more granular permission management and improving security by applying ACLs recursively to child nodes.

How to use it

To use this feature, add the apply_to_children option to an ACL configuration in the Keeper settings. This will apply the specified ACL rules not only to the targeted node but also recursively to its child nodes in the Keeper hierarchy.