chore: split CLI into multiple files (#18082)

* chore: split CLI into multiple files

* Update tests

* Who fixes the fixtures?

* Add subcommands dynamically

* Rebase

superset/cli/main.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+import importlib
+import logging
+import pkgutil
+from typing import Any, Dict
+
+import click
+from colorama import Fore, Style
+from flask.cli import FlaskGroup, with_appcontext
+
+from superset import app, appbuilder, cli, security_manager
+from superset.cli.lib import normalize_token
+from superset.extensions import db
+
+logger = logging.getLogger(__name__)
+
+
+@click.group(
+    cls=FlaskGroup, context_settings={"token_normalize_func": normalize_token},
+)
+@with_appcontext
+def superset() -> None:
+    """This is a management script for the Superset application."""
+
+    @app.shell_context_processor
+    def make_shell_context() -> Dict[str, Any]:
+        return dict(app=app, db=db)
+
+
+# add sub-commands
+for load, module_name, is_pkg in pkgutil.walk_packages(
+    cli.__path__, cli.__name__ + "."  # type: ignore
+):
+    module = importlib.import_module(module_name)
+    for attribute in module.__dict__.values():
+        if isinstance(attribute, click.core.Command):
+            superset.add_command(attribute)
+
+
+@superset.command()
+@with_appcontext
+def init() -> None:
+    """Inits the Superset application"""
+    appbuilder.add_permissions(update_perms=True)
+    security_manager.sync_role_definitions()
+
+
+@superset.command()
+@with_appcontext
+@click.option("--verbose", "-v", is_flag=True, help="Show extra information")
+def version(verbose: bool) -> None:
+    """Prints the current version number"""
+    print(Fore.BLUE + "-=" * 15)
+    print(
+        Fore.YELLOW
+        + "Superset "
+        + Fore.CYAN
+        + "{version}".format(version=app.config["VERSION_STRING"])
+    )
+    print(Fore.BLUE + "-=" * 15)
+    if verbose:
+        print("[DB] : " + "{}".format(db.engine))
+    print(Style.RESET_ALL)