This tests that strings using the first Unicode code-point of such a
multi-character token don't get recognized as "valid" number strings.
This would catch an implementation issue if the parsing code
mistakenly matched against only the first code-point of each "single
character" token.
It also adds tests of integer formatting, with multi-character sign,
and reworks some QStringView().toString()s to use u"..."_s.
Task-number: QTBUG-107801
Change-Id: I7b868ce2955bb322b3ecfc200438a21437090a0c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
da5dd84858