fix(DB): Sanitize `host` parameter for postgres databases when IPv6 address is passed

Doctrine is using `pg_connect` with the `host` parameter, this does not allow IPv6 addresses in URI notation.
So we need to extract the IP address and pass it directly

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

config/config.sample.php

 
 /**
  * Your host server name, for example ``localhost``, ``hostname``,
- * ``hostname.example.com``, or the IP address. To specify a port use
- * ``hostname:####``; to specify a Unix socket use
- * ``/path/to/directory/containing/socket`` e.g. ``/run/postgresql/``.
+ * ``hostname.example.com``, or the IP address.
+ * To specify a port use ``hostname:####``, for IPv6 addresses use the URI notation ``[ip]:port``.
+ * To specify a Unix socket use ``/path/to/directory/containing/socket``, e.g. ``/run/postgresql/``.
  */
 'dbhost' => '',
 

lib/private/DB/ConnectionFactory.php

 				$eventManager->addEventSubscriber(
 					new SQLSessionInit("SET SESSION AUTOCOMMIT=1"));
 				break;
+
 			case 'oci':
 				$eventManager->addEventSubscriber(new OracleSessionInit);
 				// the driverOptions are unused in dbal and need to be mapped to the parameters
 				unset($additionalConnectionParams['host']);
 				break;
 
+			case 'pgsql':
+				// pg_connect used by Doctrine DBAL does not support URI notation (enclosed in brackets)
+				$matches = [];
+				if (preg_match('/^\[([^\]]+)\]$/', $additionalConnectionParams['host'], $matches)) {
+					// Host variable carries a port or socket.
+					$additionalConnectionParams['host'] = $matches[1];
+				}
+				break;
+
 			case 'sqlite3':
 				$journalMode = $additionalConnectionParams['sqlite.journal_mode'];
 				$additionalConnectionParams['platform'] = new OCSqlitePlatform();