Improve handling of ArrayFlags

Why discord did it this way instead of as an integer bitfield like everything reasonable is unknowable, but this does less work to get to the same result.

discord/flags.py

@@ -25,6 +25,7 @@
 from __future__ import annotations
 
 from functools import reduce
+from operator import or_
 from typing import TYPE_CHECKING, Any, Callable, ClassVar, Dict, Iterator, List, Optional, Tuple, Type, TypeVar, overload
 
 from .enums import UserFlags
@@ -1566,7 +1567,7 @@ class ArrayFlags(BaseFlags):
     @classmethod
     def _from_value(cls: Type[Self], value: List[int]) -> Self:
         self = cls.__new__(cls)
-        self.value = reduce(lambda a, b: a | (1 << b - 1), value, 0)
+        self.value = reduce(or_, map((1).__lshift__, value), 0) >> 1
         return self
 
     def to_array(self) -> List[int]: