patch 8.2.2296: cannot use CTRL-N and CTRL-P in a popup menu

Problem:    Cannot use CTRL-N and CTRL-P in a popup menu.
Solution:   Use CTRL-N like <Down> and CTRL-P like <Up>. (closes #7614)

runtime/doc/popup.txt

@@ -309,8 +309,8 @@ popup_dialog({what}, {options})				*popup_dialog()*
 
 popup_filter_menu({id}, {key})				*popup_filter_menu()*
 		Filter that can be used for a popup. These keys can be used:
-		    j <Down>		select item below
+		    j <Down> <C-N>	select item below
-		    k <Up>		select item above
+		    k <Up> <C-P>	select item above
 		    <Space> <Enter>	accept current selection
 		    x Esc CTRL-C	cancel the menu
 		Other keys are ignored.

src/popupwin.c

@@ -2380,9 +2380,10 @@ f_popup_filter_menu(typval_T *argvars, typval_T *rettv)
     res.v_type = VAR_NUMBER;
 
     old_lnum = wp->w_cursor.lnum;
-    if ((c == 'k' || c == 'K' || c == K_UP) && wp->w_cursor.lnum > 1)
+    if ((c == 'k' || c == 'K' || c == K_UP || c == Ctrl_P)
+						      && wp->w_cursor.lnum > 1)
 	--wp->w_cursor.lnum;
-    if ((c == 'j' || c == 'J' || c == K_DOWN)
+    if ((c == 'j' || c == 'J' || c == K_DOWN || c == Ctrl_N)
 		       && wp->w_cursor.lnum < wp->w_buffer->b_ml.ml_line_count)
 	++wp->w_cursor.lnum;
     if (old_lnum != wp->w_cursor.lnum)

src/testdir/test_popupwin.vim

@@ -3797,4 +3797,10 @@ func Test_popupwin_exiting_terminal()
   endtry
 endfunc
 
+func Test_popup_filter_menu()
+  let colors = ['red', 'green', 'blue']
+  call popup_menu(colors, #{callback: {_, result -> assert_equal('green', colors[result - 1])}})
+  call feedkeys("\<c-n>\<c-n>\<c-p>\<cr>", 'xt')
+endfunc
+
 " vim: shiftwidth=2 sts=2

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2296,
 /**/
     2295,
 /**/