QAnyStringView::data lacks a purpose - add encoding(), document or deprecate

QAnyStringView is great! I learned about it recently and really like it!

However, in some areas it still feels a bit young. At some point, it is almost always needed to extract data from it and then there are some (performance-related) issues.

We have toString(), but that will allocate a new QString. Sometimes, users don’t even want a string - they want an int, float or double - or appending to a string and then a not needed allocation is pretty expensive.

I’d like to propose adding the following:

• toInt(), toFloat(), toDouble() — like QStringView has.

• QString::operator+=(QAnyStringView) and/or QStringView::writeTo(QString&) could also be useful.

But importantly, until QAnyStringView gets these, it would be really nice to be able to handle this on the user side - but that’s not easy right now, because there are no good way to use data() without knowing the encoding of the view.

So maybe add QAnyStringView::encoding() or something similar?