Add support for database schema in PostgreSQL (#8819)

* Add support for database schema

* Require setting search_path for the db user

* Add schema setting to admin/config.tmpl

* Use a schema different from default for psql tests

* Update postgres scripts to use custom schema

* Update to xorm/core 0.7.3 and xorm/xorm c37aff9b3a

* Fix migration test

Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

integrations/pgsql.ini.tmpl

@@ -7,6 +7,7 @@ HOST     = {{TEST_PGSQL_HOST}}
 NAME     = {{TEST_PGSQL_DBNAME}}
 USER     = {{TEST_PGSQL_USERNAME}}
 PASSWD   = {{TEST_PGSQL_PASSWORD}}
+SCHEMA   = {{TEST_PGSQL_SCHEMA}}
 SSL_MODE = disable
 
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