Add a new reporter customization point: reporting all assertions

By opting the JUnit and XML reporters into it, we no longer run
into problem where they underreport the results without `-s` flag.

Related to #1264, #1267, #1310

include/internal/catch_interfaces_reporter.h

@@ -42,6 +42,7 @@ namespace Catch {
 
     struct ReporterPreferences {
         bool shouldRedirectStdOut = false;
+        bool shouldReportAllAssertions = false;
     };
 
     template<typename T>

include/internal/catch_run_context.cpp

@@ -17,7 +17,7 @@ namespace Catch {
         m_config(_config),
         m_reporter(std::move(reporter)),
         m_lastAssertionInfo{ StringRef(), SourceLineInfo("",0), StringRef(), ResultDisposition::Normal },
-        m_includeSuccessfulResults( m_config->includeSuccessfulResults() )
+        m_includeSuccessfulResults( m_config->includeSuccessfulResults() || m_reporter->getPreferences().shouldReportAllAssertions )
     {
         m_context.setRunner(this);
         m_context.setConfig(m_config);