refactor(config): abstract config storage and enable dependency injection

Abstract the configuration storage mechanism to allow using custom
configurations, such as in-memory setups, when using the tool as
a library. This aligns the configuration architecture with the
session cache abstraction.

- Define ConfigInterface protocol and InMemoryConfig class
- Make CacheFile, InMemoryCache, ConfigFile, and InMemoryConfig
  explicitly inherit their interfaces
- Update MdrsService and MdrsClient to accept customizable
  config_class and config instances
- Add validation to check remote parameter consistency in
  create_connection
- Remove unused imports across command files

mdrsclient/commands/login.py

@@ -2,11 +2,7 @@ import getpass
 from argparse import Namespace
 from typing import Any
 
-from mdrsclient.api import UsersApi
 from mdrsclient.commands.base import BaseCommand
-from mdrsclient.config import ConfigFile
-from mdrsclient.connection import MDRSConnection
-from mdrsclient.exceptions import MissingConfigurationException
 
 
 class LoginCommand(BaseCommand):