introduce paths module which contains the data paths

This means that nominatim can find its data even when not called
from the command line tool.

cmake/paths-py.tmpl

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Path settings for extra data used by Nominatim (installed version).
+"""
+from pathlib import Path
+
+PHPLIB_DIR = (Path('@NOMINATIM_LIBDIR@') / 'lib-php').resolve()
+SQLLIB_DIR = (Path('@NOMINATIM_LIBDIR@') / 'lib-sql').resolve()
+DATA_DIR = Path('@NOMINATIM_DATADIR@').resolve()
+CONFIG_DIR = Path('@NOMINATIM_CONFIGDIR@').resolve()