LPS-47033 Advanced replace in CKEditor autocomplete

Hey @ipeychev,

This is an initial attempt at allowing a smarter replace mode inside the autocomplete plugin for CKEditor. You can test it in journal or blog ckeditor, by deploying the mentions portlet. I've sent you a PR for testing this: https://github.com/ipeychev/liferay-plugins/pull/29

Let me know what you think.

Thanks!