Not possible to select first point in list in a text edit

This issue is mostly annoying because even if you do Ctrl+A you can't delete everything in one press. But it also means that you can't change font size etc on the first point at all, making you have to add another line above first.

I've been looking at this issue a bit in the code and it seems like the internals of QTextDocument has a special case for when the cursor position is -1: https://github.com/qt/qtbase/blob/dev/src/gui/text/qtextdocument_p.cpp#L674

But all the way through QTextCursor there's checks and asserts to make sure pos is never -1. I assume it can happen when setBlockCharFormat is run on the first block but it should also happen for select all, select line, and in QWidgetTextControl::mouseMoveEvent when selecting above top left.

Same bug (I assume), and repro: QDS-8192