Ticket 49099 - ns workers prep
Bug Description: We wish to move to nunc-stans to control our worker
threads and async tasks.
Fix Description: This first patch moves the NS worker pool
creation to main.c, which makes it accesible to both offline
and online jobs. As well, we no longer "support" a server without
nunc-stans so remove the configure options. We still allow enable
disable of the feature however, so this has been fully tested.
https://pagure.io/389-ds-base/issue/49099
Author: wibrown
Review by: mreynolds (thanks!)