Automate deleted Dandiset recovery

We have gone through a manual process for an accidentally deleted Dandiset recovery one time, at a user's request. This issue is about creating an automatic "undelete" process that a user can initiate within the appropriate grace period.

This issue will require some discussion to properly define its scope. For example, this might start out just as admin-only automations that can assist us with the task of Dandiset recovery. A deeper option would be a user-facing control to initiate and manage the process. The latter is clearly (much) more work, at a higher level of risk, hence why a discussion is needed.

Begin by discussing and documenting the recovery scope, including the grace period and whether the first version is admin-only or user-facing. Define the recovery workflow, permissions, risks, and acceptance criteria before choosing an implementation entry point. Done means the scope is agreed and the selected undelete process is specified clearly enough to implement.

Written by the indexing model from the issue text.