replace make serve with nominatim serve command

With the website directory now tied to the project directory instead
of the build directory, it is no longer possible to use make for
running the web server.

nominatim/cli.py

@@ -11,7 +11,7 @@ import logging
 from pathlib import Path
 
 from .config import Configuration
-from .tools.exec_utils import run_legacy_script, run_api_script
+from .tools.exec_utils import run_legacy_script, run_api_script, run_php_server
 from .db.connection import connect
 from .db import status
 from .errors import UsageError
@@ -633,6 +633,28 @@ class QueryExport:
 
         return run_legacy_script(*params, nominatim_env=args)
 
+
+class AdminServe:
+    """\
+    Start a simple web server for serving the API.
+
+    This command starts the built-in PHP webserver to serve the website
+    from the current project directory. This webserver is only suitable
+    for testing and develop. Do not use it in production setups!
+
+    By the default, the webserver can be accessed at: http://127.0.0.1:8088
+    """
+
+    @staticmethod
+    def add_args(parser):
+        group = parser.add_argument_group('Server arguments')
+        group.add_argument('--server', default='127.0.0.1:8088',
+                           help='The address the server will listen to.')
+
+    @staticmethod
+    def run(args):
+        run_php_server(args.server, args.project_dir / 'website')
+
 STRUCTURED_QUERY = (
     ('street', 'housenumber and street'),
     ('city', 'city, town or village'),
@@ -895,6 +917,7 @@ def nominatim(**kwargs):
     parser.add_subcommand('refresh', UpdateRefresh)
 
     parser.add_subcommand('export', QueryExport)
+    parser.add_subcommand('serve', AdminServe)
 
     if kwargs.get('phpcgi_path'):
         parser.add_subcommand('search', APISearch)