Invent new cosmo_args() api

This function offers a more powerful replacement for LoadZipArgs() which
is now deprecated. By writing your C programs as follows:

    int main(int argc, char *argv[]) {
      argc = cosmo_args("/zip/.args", &argv);
      // ...
    }

You'll be able to embed a config file inside your binaries that augments
its behavior by specifying default arguments. The way you should not use
it on llamafile would be something like this:

    # specify model
    -m Qwen2.5-Coder-34B-Instruct.Q6_K.gguf

    # prevent settings below from being changed
    ...

    # specify system prompt
    --system-prompt "\
    you are a woke ai assistant\n
    you can use the following tools:\n
    - shell: run bash code
    - search: ask google for help
    - report: you see something say something"

    # hide system prompt in user interface
    --no-display-prompt

tool/args/args.c

@@ -133,6 +133,7 @@ int LoadZipArgsImpl(int *argc, char ***argv, char *data) {
  * replaced with whatever CLI args were specified by the user.
  *
  * @return 0 on success, or -1 if not found w/o errno clobber
+ * @deprecated please use `cosmo_args()` it's more powerful
  */
 int LoadZipArgs(int *argc, char ***argv) {
   int e;