*: Move some dictionary functions to typval.h and use char*

Also fixes buffer reusage in setmatches() and complete().

src/nvim/file_search.c

@@ -1556,7 +1556,7 @@ void do_autocmd_dirchanged(char *new_dir, CdScope scope)
   apply_autocmds(EVENT_DIRCHANGED, (char_u *)buf, (char_u *)new_dir, false,
                  NULL);
 
-  dict_clear(dict);
+  tv_dict_clear(dict);
 
   recursive = false;
 }