Expand Merge Queue: Allow librarians to submit deletion requests

### Proposal

Fairly often, in the librarian Slack channel people request entries to be deleted (calendars, etc) that aren't suited to merging.
I'm sure some people also just submit the request form to ask this to be done.

To ease this burden we should extent the merge queue to also have a deletion queue.
@seabelis gave a thumbs up to this idea [here](https://internetarchive.slack.com/archives/C0119PRDV46/p1731727382666259).
Preferably worded in a way that says “this is not a book” rather than “delete this”.

### Justification

It makes it easier for librarians to keep our dataset clean.
It also makes once consistent place for super librarians to review such requests.

The impact of this is relatively small as deletions are much fewer than merges but it will be yet another tool in our belt for a great experience of contributors.

### Breakdown

#### Requirements Checklist

This will need to be broken down more but initial thoughts
* [ ] It should basically mirror the current merge queue with the exception of
* You only need to select one item to suggest a deletion

#### Related files

*

#### Stakeholders

* @seabelis

#### Instructions for Contributors

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