vim-patch:8.2.4565: no command line completion for :breakadd and :breakdel

Problem:    No command line completion for :breakadd and :breakdel.
Solution:   Add completion for :breakadd and :breakdel. (Yegappan Lakshmanan,
            closes vim/vim#9950)

6e2e2cc95b

src/nvim/vim.h

@@ -154,6 +154,7 @@ enum {
   EXPAND_MAPCLEAR,
   EXPAND_ARGLIST,
   EXPAND_DIFF_BUFFERS,
+  EXPAND_BREAKPOINT,
   EXPAND_CHECKHEALTH,
   EXPAND_LUA,
 };