added Coverlet result files as a Code Coverage Tool (#3252)

VisualStudio.gitignore

@@ -137,6 +137,9 @@ _TeamCity*
 .axoCover/*
 !.axoCover/settings.json
 
+# Coverlet is a free, cross platform Code Coverage Tool
+coverage*[.json, .xml, .info]
+
 # Visual Studio code coverage results
 *.coverage
 *.coveragexml