Add __format__ overrides to complex, float, int, and str (#14523)

Author: brianschubert

stdlib/builtins.pyi

@@ -349,6 +349,7 @@ class int:
     def __hash__(self) -> int: ...
     def __bool__(self) -> bool: ...
     def __index__(self) -> int: ...
+    def __format__(self, format_spec: str, /) -> str: ...
 
 class float:
     def __new__(cls, x: ConvertibleToFloat = ..., /) -> Self: ...
@@ -410,6 +411,7 @@ class float:
     def __abs__(self) -> float: ...
     def __hash__(self) -> int: ...
     def __bool__(self) -> bool: ...
+    def __format__(self, format_spec: str, /) -> str: ...
     if sys.version_info >= (3, 14):
         @classmethod
         def from_number(cls, number: float | SupportsIndex | SupportsFloat, /) -> Self: ...
@@ -446,6 +448,7 @@ class complex:
     def __abs__(self) -> float: ...
     def __hash__(self) -> int: ...
     def __bool__(self) -> bool: ...
+    def __format__(self, format_spec: str, /) -> str: ...
     if sys.version_info >= (3, 11):
         def __complex__(self) -> complex: ...
     if sys.version_info >= (3, 14):
@@ -642,6 +645,7 @@ class str(Sequence[str]):
     @overload
     def __rmul__(self, value: SupportsIndex, /) -> str: ...  # type: ignore[misc]
     def __getnewargs__(self) -> tuple[str]: ...
+    def __format__(self, format_spec: str, /) -> str: ...
 
 class bytes(Sequence[int]):
     @overload