Add Spree::PermissionConfiguration to manage role-based permission sets via code

Add Spree::PermissionConfiguration to manage role-based permission sets via code: a task in bird-critic-1.5-full-300 (Harbor dataset). This PR introduces a programmatic API for configuring role-based permissions in Spree, a Ruby e-commerce platform. It adds Spree::PermissionConfiguration — a…

The task

This PR introduces a programmatic API for configuring role-based permissions in Spree, a Ruby e-commerce platform. It adds `Spree::PermissionConfiguration` — a registry that maps role names to one or more `Spree::PermissionSets::Base` subclasses — and reworks `Spree.permissions` to use this new API. A…

Part of kochsnow/bird-critic-1.5-full-300.