Avoid control characters in Neovim terminal buffer name

- With 'title', run command from temp script if it has control chars
- Raw ESC in buffer name leaked through title and drew garbage

Fix #4941

plugin/fzf.vim

@@ -1104,6 +1104,12 @@ function! s:execute_term(dict, command, temps) abort
       let fzf.temps.batchfile = s:fzf_tempname().'.bat'
       call s:writefile(s:wrap_cmds(a:command), fzf.temps.batchfile)
       let command = fzf.temps.batchfile
+    elseif has('nvim') && &title && a:command =~ '[[:cntrl:]]'
+      " Neovim puts the command in the buffer name, which can end up raw in
+      " the terminal title (#4941)
+      let fzf.temps.shellscript = s:fzf_tempname()
+      call s:writefile([a:command], fzf.temps.shellscript)
+      let command = 'sh '.fzf#shellescape(fzf.temps.shellscript)
     else
       let command = a:command
     endif