Implement the missing overload to handle UTF-8 specific data types,
including char8_t (C++20), char, uchar and signed char.
Introduce the helper function 'assign_helper_char8' which handles the
non-contiguous_iterator case. The contiguous_iterator case is already
handled by the QAnyStringView overload.
Include 'qstringconverter.h' at the end of the file, since it can't
be included at the top due to diamond dependency conflicts.
QStringDecoder is an implementation detail we don't want users to
depend on when using assign(it, it). It would be unnatural to not
be able to use a function just because we didn't include an
apparently unrelated header.
[ChangeLog][QtCore][QString] Enabled assign() for UTF-8 data types.
Fixes: QTBUG-114208
Change-Id: Ia39bbb70ca105a6bbf1a131b2533f29a919ff66d
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
016addc201