output an all errors to XML document file

EPUBCheck's output an assessment XML document file that errors are limited to 25.
We would like to see this limitation relaxed, as we need a complete log to create a valid ePub.

> private static final int MAX_LOCATIONS = 25;
https://github.com/w3c/epubcheck/blob/main/src/main/java/com/adobe/epubcheck/reporting/CheckMessage.java#L16