patch 8.2.3580: gj does not move properly with a wide character

Problem:    gj does not move properly with a wide character.
Solution:   Move one to the right. (Christian Brabandt, closes #8702)

src/testdir/test_normal.vim

@@ -3423,4 +3423,16 @@ func Test_normal_count_after_operator()
   bw!
 endfunc
 
+func Test_normal_gj_on_extra_wide_char()
+  new | 25vsp
+  let text='1 foooooooo ar e  ins‍zwe1 foooooooo ins‍zwei' .
+         \ ' i drei vier fünf sechs sieben acht un zehn elf zwöfl' .
+         \ ' dreizehn v ierzehn fünfzehn'
+  put =text
+  call cursor(2,1)
+  norm! gj
+  call assert_equal([0,2,25,0], getpos('.'))
+  bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab