Need to use QConcatenable<>::ConvertTo for SFINAE, the forwarded type
alias in QStringBuilder itself doesn't work.
[ChangeLog][QtCore][QAnyStringView/QStringBuilder] Implicit conversion
from QStringBuilder to QAnyStringView now works as advertised.
Pick-to: 6.2
Fixes: QTBUG-98138
Change-Id: I1c300675cf43b13017bc56398ae5d8c1c51e64fe
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
b7f4041669