[ChangeLog][Potentially Source-Incompatible Changes] The qtextstream
header no longer includes <QString>, <QStringEncoder> and
<QStringDecoder>. Code which relied on the implicit inclusion of those
classes might now need to include the headers explicitly.
Task-number: QTBUG-97601
Change-Id: Ifb8c8452026195a772c0588dbbbc53fb51cac548
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>