Zabbix

...G...... [ZBXCTR-13] added custom query support for PostgreSQL plugin

# Conflicts:
#	ChangeLog.d/feature/ZBXCTR-13
#	src/go/conf/zabbix_agent2.conf
#	src/go/conf/zabbix_agent2.win.conf
#	src/go/go.mod
#	src/go/go.sum
#	src/go/pkg/conf/session.go
#	src/go/pkg/metric/metric.go
#	src/go/pkg/metric/metric_test.go
#	src/go/pkg/metric/validators.go
#	src/go/pkg/metric/validators_test.go
#	src/go/pkg/uri/uri.go
#	src/go/pkg/uri/uri_test.go
#	src/go/plugins/postgres/README.md
#	src/go/plugins/postgres/config.go
#	src/go/plugins/postgres/conn.go
#	src/go/plugins/postgres/error.go
#	src/go/plugins/postgres/uri.go
#	templates/db/postgresql_agent2/README.md
#	templates/db/postgresql_agent2/template_db_postgresql_agent2.yaml

(cherry picked from commit 9ea4346310a5b4d699865ea823c5ddabd0e8d9b1)