kateviewinternal: accept surrogate category character
This is added to QInputControl::isAcceptableInput in https://github.com/qt/qtbase/commit/e688b99995b8c624dbcea296c99fb89262d29e15.
FYI: see https://github.com/qt/qtbase/blob/dev/src/gui/text/qinputcontrol.cpp#L21C6-L21C38
Edited by Yifan Zhu