includeLocales not active when enableInSFC is false

[Glandos]

Module versions (please complete the following information):

• Vue CLI: 5.0.8
• vue-cli-plugin-i18n: 2.3.1

#243 introduces a feature to include locales using the message compiler. But reading the code, it seems that it is not active if enableSFC is false. Is it on purpose? In this case, the documentation should be updated. Otherwise, the condition should be adapted.