KFormat: Use KFormat::JEDECBinaryDialect as default
That is using "Kb" instead of "Kib" by default for file sizes.
This was chosen as default in 3.5, but some code wasn't changed, or this was set some place else.
We can see it in https://invent.kde.org/frameworks/kdelibs4support/-/blob/kf5/src/kdecore/klocale.h?ref_type=heads#L526
Unless the default was changed back sometimes on purpose after KDE 3.5 ?
I think this is more aligned to what our users are accustomed to.
Related: https://bugs.kde.org/show_bug.cgi?id=453854 https://discuss.kde.org/t/how-to-configure-plasma-5-to-use-mb-instead-of-mib/5660/2
cc @ngraham
kio will need a similar patch.