Update SonarC#: Unit Tests total and skipped numbers are not consistent

[Evangelink]

Currently the plugin is doing different calculation based on the test framework used. All of them produce results that are hard to understand (as they don't match the result report ones).

The idea of this ticket is to make sure to use the same standard for all frameworks (and also to report in the same way as for other plugins).

MSTest/VSTest

• Unit Tests: executed
• Errors: error
• Failures: timeout + failed + aborted
• Skipped: total - executed

NUnit

• Unit Tests: total - skipped - inconclusive - ignored (test-results) or total - skipped - inconclusive (test-run)
• Errors: errors (test-results) or sum all nested test-case Error
• Failures: failures (test-results) or failed (test-run)
• Skipped: skipped + inconclusive + ignored (test-results) or skipped + inconclusive (test-run)

XUnit

• Unit Tests: total - skipped
• Errors: errors
• Failures: failed
• Skipped: skipped