[3.12] gh-124008: Fix calculation of the number of written bytes for the Windows...

[3.12] gh-124008: Fix calculation of the number of written bytes for the Windows console (GH-124059) (GH-127326)

Since MultiByteToWideChar()/WideCharToMultiByte() is not reversible if
the data contains invalid UTF-8 sequences, use binary search to
calculate the number of written bytes from the number of written
characters.

Also fix writing incomplete UTF-8 sequences.

Also fix handling of memory allocation failures.
(cherry picked from commit 3cf83d91a5baf3600dd60f7aaaf4fb6d73c4b8a9)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>