This is the follow-up issue of #15370 and Embed in-text nature in reference marks for CSL citations, which extends the solution to invisible(empty) citations.

This issue involves two parts:

1. Use enum (e.g. CITATION_TYPE{NORMAL, IN_TEXT, EMPTY}) to replace boolean var in the method signature.
2. Redesign and re-implement reference mark format, as well as the parsing logic.