Re-add Force Font DPI spinbox on Wayland
People are using this feature to work around Wayland's terrible fractional scaling implementation that makes everything super blurry. I can't in good conscience tell them to use it anyway because it really does look so bad. :( See https://bugs.kde.org/show_bug.cgi?id=433269.
This reverts commit 65defdde This reverts commit 40afa58a
This should be safe to cherry-pick because the string it adds is one that was removed earlier, so it should still be present in the localization system.
BUG: 433115 FIXED-IN: 5.21.2