Change QFormDataBuilderPrivate to store a vector of
QFormDataPartBuilderPrivates and pimplify QFormDataPartBuilder such that
it stores a pointer to the QFormDataBuilderPrivate and an index into the
vector. This makes it robust against QFDP::m_parts reallocations and we
can make QFDBP copyable which has the benefit that if the user wants to
"go back" to an earlier part, she can do so by storing the result of the
original part() call by value.
Found in API review.
Task-number: QTBUG-125985
Change-Id: I56e9018e539457e9494751bdb62509f84a680889
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit aca8235c753d673abe7442cdf8b628fe4e05c471)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
04787eef80