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/usercmd.c

@@ -95,6 +95,7 @@ static const char *command_complete[] = {
   [EXPAND_TAGS_LISTFILES] = "tag_listfiles",
   [EXPAND_USER] = "user",
   [EXPAND_USER_VARS] = "var",
+  [EXPAND_BREAKPOINT] = "breakpoint",
 };
 
 /// List of names of address types.  Must be alphabetical for completion.