Add validation configuration/mapping XSDs for 3.1 version

[marko-bekhta]

https://github.com/jakartaee/validation/tree/main/src/main/xsd does not include XSDs for Jakarta Validation 3.1. While there were no changes in this area, it would be good to have the XSDs there, even if just for the 3.1 in the XMLs:

<validation-config
    xmlns="https://jakarta.ee/xml/ns/validation/configuration"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://jakarta.ee/xml/ns/validation/configuration https://jakarta.ee/xml/ns/validation/validation-configuration-3.1.xsd"
    version="3.1">

    <property name="smth">value</property>
</validation-config>

and if we do so, the XSDs should be available through https://jakarta.ee/xml/ns/validation/

[jungm]

Generally support this and also found it odd when moving Apache BVal to 3.1 but I'm wondering if this is something that can even be done in a patch release? Technically this changes the validation 3.1 spec imo