Split ESQL functions/operators docs files (#123904) (#124214)
* Port from asciidocalypse
* Fix links for operator lists
* Remove unused image files after moving/editing them
* Fix lists links
* Fix like/rlike links
* Fix remaining bad references to /elasticsearch/docs
* Fix logstash and beats references
* Fix logstash and beats references
* Fix image links
(cherry picked from commit efe7379e67
)
Co-authored-by: Craig Taverner <craig@amanzi.com>