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/config.py

@@ -1,6 +1,7 @@
 import configparser
 import os
-from typing import Final
+import threading
+from typing import Final, Protocol, runtime_checkable
 
 import validators
 
@@ -9,7 +10,56 @@ from mdrsclient.settings import CONFIG_DIRNAME
 from mdrsclient.utils import FileLock
 
 
-class ConfigFile:
+@runtime_checkable
+class ConfigInterface(Protocol):
+    remote: str
+
+    def list(self) -> list[tuple[str, str]]: ...
+    @property
+    def url(self) -> str | None: ...
+    @url.setter
+    def url(self, url: str) -> None: ...
+    @url.deleter
+    def url(self) -> None: ...
+
+
+class InMemoryConfig(ConfigInterface):
+    __configs: dict[str, str] = {}
+    __lock: threading.Lock = threading.Lock()
+    remote: str
+
+    def __init__(self, remote: str) -> None:
+        self.remote = remote
+
+    def list(self) -> list[tuple[str, str]]:
+        with self.__lock:
+            return list(self.__configs.items())
+
+    @property
+    def url(self) -> str | None:
+        with self.__lock:
+            return self.__configs.get(self.remote)
+
+    @url.setter
+    def url(self, url: str) -> None:
+        if not validators.url(url):
+            raise IllegalArgumentException("malformed URI sequence")
+        with self.__lock:
+            self.__configs[self.remote] = url
+
+    @url.deleter
+    def url(self) -> None:
+        with self.__lock:
+            if self.remote in self.__configs:
+                del self.__configs[self.remote]
+
+    @classmethod
+    def clear(cls) -> None:
+        with cls.__lock:
+            cls.__configs.clear()
+
+
+class ConfigFile(ConfigInterface):
     OPTION_URL: Final[str] = "url"
     CONFIG_FILENAME: Final[str] = "config.ini"
     remote: str