fix(collections): add deque reverse multiplication

Declare `deque.__rmul__` so type checkers accept multiplication with
an integer on the left. Add regression coverage for the reported
false positive.

Refs: #16034
Signed-off-by: Jason Scheffel <contact@jasonscheffel.com>

Author: jason-scheffel

stdlib/@tests/test_cases/collections/check_deque.py

@@ -0,0 +1,4 @@
+from collections import deque
+from typing_extensions import assert_type
+
+assert_type(3 * deque([1, 2, 3]), deque[int])

stdlib/collections/__init__.pyi

@@ -277,6 +277,7 @@ class deque(MutableSequence[_T]):
     def __iadd__(self, value: Iterable[_T], /) -> Self: ...
     def __add__(self, value: Self, /) -> Self: ...
     def __mul__(self, value: int, /) -> Self: ...
+    def __rmul__(self, value: int, /) -> Self: ...
     def __imul__(self, value: int, /) -> Self: ...
     def __lt__(self, value: deque[_T], /) -> bool: ...
     def __le__(self, value: deque[_T], /) -> bool: ...