Subject: Add TOC object entry support for C++

Feature or Bugfix

• Feature

Purpose

• Add TOC object entry support for C++

Detail

• object entries from the cpp domain are added to the table of contents when toc_object_entries = True in the config
• when toc_object_entries_show_parents = "domain" in the config, the TOC entries omit the namespaces added by the cpp:namespace and cpp:namespace-push directives.