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/csv.pyi

@@ -76,9 +76,9 @@ class DictReader(Generic[_T], Iterator[_DictReadMapping[_T | Any, str | Any]]):
         self,
         f: Iterable[str],
         fieldnames: Sequence[_T],
-        restkey: str | None = ...,
-        restval: str | None = ...,
-        dialect: _DialectLike = ...,
+        restkey: str | None = None,
+        restval: str | None = None,
+        dialect: _DialectLike = "excel",
         *,
         delimiter: str = ...,
         quotechar: str | None = ...,
@@ -93,10 +93,10 @@ class DictReader(Generic[_T], Iterator[_DictReadMapping[_T | Any, str | Any]]):
     def __init__(
         self: DictReader[str],
         f: Iterable[str],
-        fieldnames: Sequence[str] | None = ...,
-        restkey: str | None = ...,
-        restval: str | None = ...,
-        dialect: _DialectLike = ...,
+        fieldnames: Sequence[str] | None = None,
+        restkey: str | None = None,
+        restval: str | None = None,
+        dialect: _DialectLike = "excel",
         *,
         delimiter: str = ...,
         quotechar: str | None = ...,