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

[PostGIS]

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

 After lots of back and forth, it seems this **may** work:

 * for schema, use identifier escaping rules to produce a double-quoted
 string, and afterwards remove the first and last double-quote character.
 * do the same for the table
 * pass geometry column as is

 Which means that when calling, schema and table name have to first be
 encoded as identifiers, remove first/last `"`, and then encode using
 literal string encoding. The geometry must only be literally encoded...
 Uncertain of this, but seems to work in some testing...
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Ticket URL: <https://trac.osgeo.org/postgis/ticket/5697#comment:3>
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