refactor: Make all fetchers as an optional dependency group

+ Removing some dead code

scrapling/engines/toolbelt/custom.py

@@ -2,8 +2,10 @@
 Functions related to custom types or type checking
 """
 
+from functools import lru_cache
 from email.message import Message
 
+from scrapling.core.utils import log
 from scrapling.core._types import (
     Any,
     Dict,
@@ -12,7 +14,6 @@ from scrapling.core._types import (
     Tuple,
 )
 from scrapling.core.custom_types import MappingProxyType
-from scrapling.core.utils import log, lru_cache
 from scrapling.parser import Selector, SQLiteStorageSystem