Since the changes of 4d76a87015 (Make wxSearchCtrl inherit from
wxTextEntry in all ports, 2023-07-09, see #23697) GetEditHWND() returned
null for wxSearchCtrl which was considered to be correct because all
wxTextEntry functions were supposed to be forwarded to wxSearchTextCtrl
anyhow.
This wasn't really correct, however, as GetEditHWND() was also called
from SetHint(), resulting in an assert failure and falling back on
generic hint implementation which, while mostly working, suffers from
some problems that the native implementation doesn't have.
So make this function return the actual HWND used by the associated text
entry to fix this and allow SetHint() to work as before and also
forestall any problems due to not having the right HWND in the future.
See #23983.
Closes#23975.
9d06e4c4a7