runtime(new-tutor): escape tutor filename

If Vim is installed into the Windows "Program Files" directory the tutor
path name contains spaces and must therefore be quoted before passing to
:drop.

closes: #18742

Signed-off-by: Andrey Starodubtsev <andrey.starodubtsev@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: andrey-starodubtsev

runtime/autoload/tutor.vim

@@ -211,7 +211,7 @@ function! tutor#TutorCmd(tutor_name)
     endif
 
     call tutor#SetupVim()
-    exe "drop ".l:to_open
+    exe "drop ".fnameescape(l:to_open)
     call tutor#EnableInteractive(v:true)
 endfunction