Add support for importing an existing Postgres database

roles/matrix-server/defaults/main.yml

@@ -418,6 +418,7 @@ matrix_ssl_log_dir_path: "{{ matrix_ssl_base_path }}/log"
 
 # Variables to Control which parts of the role run.
 run_setup: true
+run_import_postgres: true
 run_upgrade_postgres: true
 run_start: true
 run_register_user: true