gh-108590: Improve sqlite3 docs on encoding issues and how to handle those (#108699)

Add a guide for how to handle non-UTF-8 text encodings.
Link to that guide from the 'text_factory' docs.

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>
Co-authored-by: Corvin <corvin@corvin.dev>
Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>