Include graphics objects with hidden handles in axes limit calculation (bug #63095). * libinterp/corefcn/graphics.cc (get_children_limits): Get handles to all axes children including those with hidden handle visibility. Add BIST. * libinterp/corefcn/graphics.in.h (text::update_position): Do not automatically change "zliminclude" property. Axes labels are implemented as text objects, and we don't want their extent to be included in the axis limit calculation.

## Test duplicate subfunctions
function x = duplicate_subfunction ()
  x = 1;
endfunction

function y = duplicate_subfcn_1 ()
  y = 2;
endfunction

function z = duplicate_subfcn_1 ()
  z = 3;
endfunction