Port some improvements from Learn@WU codebase: - check whether chat room exists exploits cache - chat room retrieval enriches with some acs_objects metadataFix potential errors when we try entering a chat room that has been deleted and check for its activity status
- Introduce new proc ad_sanitize_filename implementing current best practices for ensuring a valid filename on most filesystems.- Use it in every place where filename sanitization is performed in the code and deprecate fs::remove_special_file_system_characters.TODO deprecate also util_text_to_html? Use case of sanitizing urls and filenames might have different requirements.
