suggestion: Add JUnit xml export

[arthur-devialet]

Would be very useful to add support for JUnit xml export because Jenkins natively understands it

Refs:

• Jenkins "official" valgrind plugins is bugged and no longer maintained: https://issues.jenkins.io/browse/JENKINS-50558
• Found some "draft" scripts that do it: https://humdi.net/wiki/tips/valgrind-to-xunit-xml-converter but the parser of this repo seems more robust
• https://pypi.org/project/junit-xml/ could be use for the export instead of writing the output xml itself