vim-patch:9.0.1783: Display issues with virt text smoothscroll and showbreak

Problem:  Wrong display with wrapping virtual text or unprintable chars,
          'showbreak' and 'smoothscroll'.
Solution: Don't skip cells taken by 'showbreak' in screen lines before
          "w_skipcol". Combined "n_skip" and "skip_cells".

closes: vim/vim#12597

b557f48982

src/nvim/charset.c

@@ -991,6 +991,7 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
   chartabsize_T cts;
   bool on_NUL = false;
   init_chartabsize_arg(&cts, wp, pos->lnum, 0, line, line);
+  cts.cts_max_head_vcol = -1;
 
   // This function is used very often, do some speed optimizations.
   // When 'list', 'linebreak', 'showbreak' and 'breakindent' are not set