fix(tui): v:argv does not report the original argv[0] #24015

Problem:
Since TUI was moved to another process 2448816956
v:argv and v:progname don't report the original argv[0].
    ["/usr/bin/nvim", "--embed", ...]

Solution:
Use argv[0] instead of VV_PROGPATH in ui_client_start_server().
Fix #23953

src/nvim/ui_client.c

@@ -43,7 +43,7 @@ uint64_t ui_client_start_server(int argc, char **argv)
   varnumber_T exit_status;
   char **args = xmalloc(((size_t)(2 + argc)) * sizeof(char *));
   int args_idx = 0;
-  args[args_idx++] = xstrdup(get_vim_var_str(VV_PROGPATH));
+  args[args_idx++] = xstrdup(argv[0]);
   args[args_idx++] = xstrdup("--embed");
   for (int i = 1; i < argc; i++) {
     args[args_idx++] = xstrdup(argv[i]);