## Description, Context and related Issue

The function `edition:details($uri)?name` would return an element node
instead of a string value, thus the endpoint `getEdition.xql` returns
e.g. `"name" : "<editionName
xmlns=\"http://www.edirom.de/ns/1.3\">Pintos-Edirom von Salome
Obert</editionName>"` (among other properties).

This PR fixes this to return only the string value and refactors another
function to not duplicate code.

## Steps to reproduce 

Check the Ajax request to `getEdition.xql` which is loaded at every star
of the Edirom:
<img width="1512" alt="Bildschirmfoto 2025-01-14 um 18 41 29"
src="https://github.com/user-attachments/assets/ea67eac0-4d52-4f54-b5a2-0bd13ada1e97"
/>
(The screenshot already displays the fixed version)

## How Has This Been Tested?
With the Pintos data

## Types of changes
- Bug fix (non-breaking change which fixes an issue)
- Improvement
- Refactoring

## Overview
- I have updated the inline documentation accordingly.
- I have performed a self-review of my code, according to the [style
guide](https://github.com/Edirom/Edirom-Online/blob/develop/STYLE-GUIDE.md)
- I have read the
[CONTRIBUTING](https://github.com/Edirom/Edirom-Online/blob/develop/CONTRIBUTING.md)
document.
- All new and existing tests passed.