We need to explicitly generate this event from the char hook handler as
we don't get the normal WM_CHAR for it, it is apparently intercepted by
the window proc installed by the auto-completing code, so check if
wxTE_PROCESS_ENTER is used for the text entry and call a special new
MSWProcessSpecialKey() method to do the right thing if it is.
Similarly, handle Tab presses correctly if wxTE_PROCESS_TAB is used.
Closes#12613.
5a949efc5c