Kedro CLI startup time made shorter

- server.py: Moved `DEFAULT_HOST` and `DEFAULT_PORT` to `constants.py`
- launchers/cli.py: Moved `from kedro_viz.server ...` statement to
  viz function

Signed-off-by: Konrad Sikorski <znfgnu@gmail.com>

package/kedro_viz/constants.py

@@ -5,3 +5,6 @@
 DEFAULT_REGISTERED_PIPELINE_ID = "__default__"
 KEDRO_VERSION = VersionInfo.parse(kedro.__version__)
 ROOT_MODULAR_PIPELINE_ID = "__root__"
+
+DEFAULT_HOST = "127.0.0.1"
+DEFAULT_PORT = 4141

package/kedro_viz/launchers/cli.py

@@ -11,8 +11,8 @@
 from watchgod import RegExpWatcher, run_process
 
 from kedro_viz import __version__
+from kedro_viz.constants import DEFAULT_HOST, DEFAULT_PORT
 from kedro_viz.integrations.pypi import get_latest_version, is_running_outdated_version
-from kedro_viz.server import DEFAULT_HOST, DEFAULT_PORT, is_localhost, run_server
 
 
 @click.group(name="Kedro-Viz")
@@ -82,6 +82,7 @@ def commands():  # pylint: disable=missing-function-docstring
 )
 def viz(host, port, browser, load_file, save_file, pipeline, env, autoreload, params):
     """Visualise a Kedro pipeline using Kedro viz."""
+    from kedro_viz.server import is_localhost, run_server
     installed_version = VersionInfo.parse(__version__)
     latest_version = get_latest_version()
 

package/kedro_viz/server.py

@@ -11,13 +11,12 @@
 
 from kedro_viz.api import apps
 from kedro_viz.api.rest.responses import EnhancedORJSONResponse, get_default_response
+from kedro_viz.constants import DEFAULT_HOST, DEFAULT_PORT
 from kedro_viz.data_access import DataAccessManager, data_access_manager
 from kedro_viz.database import create_db_engine
 from kedro_viz.integrations.kedro import data_loader as kedro_data_loader
 from kedro_viz.models.experiment_tracking import Base
 
-DEFAULT_HOST = "127.0.0.1"
-DEFAULT_PORT = 4141
 DEV_PORT = 4142