Process query string on target of (page) xref
If an xref target ends in a query string, the query string should be isolated from the page ID and added back on to the resolved URL of the generated link.
Currently, the query string is treated as part of the page ID, which prevents the page from being resolved.
Generally, Antora doesn't do anything with the query string, but the target page may rely on it.
An alternative is to support a custom attribute.
However, this feels less natural.