Enhancement: add report.xml providing

[corvinusy]

Hi. There is a necessity to provide test reports to file (i.e. xml) like junit or other mature testing frameworks do. Something like

go test --report-xml="/path/to/test-report.xml" .

Available external tools (like 'go-junit-report') cannot see Convey() cases and do not provide assertion fail details. Is this possible? Thank you

[buzzdan]

i need this too