vim-patch:8.2.4343: when reloading not all properties are detected

Problem:    When reloading not all properties are detected.
Solution:   Add the "edit" value to v:fcs_choice. (Rob Pilling, closes vim/vim#9579)
8196e94a8b

Cherry-pick some test changes from patch 8.1.1826.

src/nvim/message.c

@@ -3464,6 +3464,7 @@ void msg_advance(int col)
 ///
 /// @param textfiel  IObuff for inputdialog(), NULL otherwise
 /// @param ex_cmd  when TRUE pressing : accepts default and starts Ex command
+/// @returns 0 if cancelled, otherwise the nth button (1-indexed).
 int do_dialog(int type, char_u *title, char_u *message, char_u *buttons, int dfltbutton,
               char_u *textfield, int ex_cmd)
 {