Add more defaults to the stdlib (#9606)

Continuing work towards #8988.

The first five commits were created using stubdefaulter on various Python versions; the following commits were all created manually by me to fix various problems. The main things this adds that weren't present in #9501 are:

- Defaults in Windows-only modules and Windows-only branches (because I'm running a Windows machine)
- Defaults in non-py311 branches
- Defaults for float parameters
- Defaults for overloads

stdlib/wsgiref/headers.pyi

@@ -17,7 +17,7 @@ class Headers:
     @overload
     def get(self, name: str, default: str) -> str: ...
     @overload
-    def get(self, name: str, default: str | None = ...) -> str | None: ...
+    def get(self, name: str, default: str | None = None) -> str | None: ...
     def keys(self) -> list[str]: ...
     def values(self) -> list[str]: ...
     def items(self) -> _HeaderList: ...