gh-75459: Doc: C API: Improve object life cycle documentation (GH-125962)

* Add "cyclic isolate" to the glossary.
  * Add a new "Object Life Cycle" page.
  * Improve docs for related API, with special focus on cross-references and warnings

Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>