[PostGIS] #5697: fix or document id escaping for ST_EstimatedExtent params

[PostGIS]

#5697: fix or document id escaping for ST_EstimatedExtent params
----------------------+---------------------------
  Reporter:  Yuri     |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 3.4.3
 Component:  postgis  |    Version:  3.4.x
Resolution:           |   Keywords:
----------------------+---------------------------
Comment (by pramsey):

 @robe, I dunno what you think about this one, I don't know what to put in
 doco, and in a perfect world I would go back and just change the function
 so the arguments are directly regclass arguments, but doing so now *might*
 break existing users (of which there area a lot of important ones, as
 every postgis client calls estimated extent) and would also involve
 explicitly dropping the current signature (or it would interpose itself on
 the case where a user calls using text parameters, instead of allowing
 autocasting to work its magic and convert to regclass).
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5697#comment:5>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.