Designs tab: Deleting a design doesn't actually delete [Backend 1: Enum]

About

This is one of four issues for the backend implementation of #38048.

Tasks

Task is to change the DesignManagement::Action.event enum.

1. Rename existing :deletion event enum in DesignManagement::Action to :archival.
2. Add a new :deletion to the DesignManagement::Action event enum.