CREATE or UPDATE extension fails if layer / topology table exists in the public schema

[Algunenano]

CREATE extension fails when either public.layer or public.topology exists, which blocks installation or updating the extension.

Example with creation:

postgis_test=# create extension postgis_topology;
CREATE EXTENSION
postgis_test=# drop extension postgis_topology;
DROP EXTENSION
postgis_test=# create table layer ( a int );
CREATE TABLE
postgis_test=# create extension postgis_topology;
ERROR:  table "layer" is not a member of the extension being created

With the update:

postgis_test=# create extension postgis_topology;
CREATE EXTENSION
postgis_test=# create table layer ( a int );
CREATE TABLE
"2.5.0rc1dev"      "2.5.0rc1devnext"  
postgis_test=# \dt public.*
              List of relations
 Schema |      Name       | Type  |  Owner   
--------+-----------------+-------+----------
 public | layer           | table | postgres
 public | spatial_ref_sys | table | postgres
(2 rows)

postgis_test=# \dt topology.*
           List of relations
  Schema  |   Name   | Type  |  Owner   
----------+----------+-------+----------
 topology | layer    | table | postgres
 topology | topology | table | postgres
(2 rows)

postgis_test=# alter extension postgis_topology update TO "2.5.0rc1devnext" ;
ERROR:  table "layer" is not a member of the extension being created

[Algunenano]

WIP in ​https://github.com/postgis/postgis/pull/300

I'll do some manual tests and try to see how long back do we want to port the fix.

[algunenano]

In 16798:

Use qualified names in topology extension install

References #4160

[algunenano]

In 16799:

Use qualified names in topology extension install

References #4160

[algunenano]

In 16800:

Use qualified names in topology extension install

References #4160

[algunenano]

In 16801:

Use qualified names in topology extension install

Closes #4160
Closes ​https://github.com/postgis/postgis/pull/300

[algunenano]

In 16802:

Use qualified names in topology extension install

References #4160