Add option to add bookmark name

`/bookmark add|update` got `name` field.
By default localpart of JID is used (like before) but now we can set the
name ourselves.

Regards https://github.com/profanity-im/profanity/issues/697

src/command/cmd_ac.c

@@ -615,6 +615,7 @@ cmd_ac_init(void)
     autocomplete_add(bookmark_property_ac, "nick");
     autocomplete_add(bookmark_property_ac, "password");
     autocomplete_add(bookmark_property_ac, "autojoin");
+    autocomplete_add(bookmark_property_ac, "name");
 
 #ifdef HAVE_LIBOTR
     otr_ac = autocomplete_new();