Ignore .idea/sonarlint.xml

As mentioned in https://community.sonarsource.com/t/is-the-file-idea-idea-idea-sonarlint-xml-intended-to-be-under-source-control/121119, the `sonarlint.xml` file should be in the `.gitignore`.

Author: bartlaarhoven

Global/JetBrains.gitignore

@@ -63,6 +63,7 @@ atlassian-ide-plugin.xml
 
 # SonarLint plugin
 .idea/sonarlint/
+.idea/sonarlint.xml # see https://community.sonarsource.com/t/is-the-file-idea-idea-idea-sonarlint-xml-intended-to-be-under-source-control/121119
 
 # Crashlytics plugin (for Android Studio and IntelliJ)
 com_crashlytics_export_strings.xml