Add support for Kover test coverage reports for Android variants

[thepoofy]

The team behind Kotlin has built a new test coverage framework called Kover. Kover integrates easily with Android projects written in Kotlin and generates files compatible with JaCoCo.

This works fine for the CodeCov CLI when reports are generated for all variants. eg: ./gradlew koverXmlReport because the files generated are called report.xml.

However, when tests and test coverage are only generated for specific variants, the file name can be variable. eg: reportDebug.xml, reportRelease.xml or more generally report*.xml because the developers can and often do define custom variants within their projects.

For this reason, I'm requesting that the allowed file format be updated from report.xml to report*.xml.