feat(xml-logs): finish tests

Signed-off-by: Rachel Powers <508861+Ryex@users.noreply.github.com>

launcher/launch/LogModel.cpp

@@ -166,3 +166,11 @@ bool LogModel::isOverFlow()
 {
     return m_numLines >= m_maxLines && m_stopOnOverflow;
 }
+
+
+MessageLevel::Enum LogModel::previousLevel() {
+    if (!m_content.isEmpty()) {
+        return m_content.last().level;
+    }
+    return MessageLevel::Unknown;
+}