Benchmarking CLI improvements

A few small things that would be great to improve in benchmarking CLI:

1. We should use `structop` instead of `clap` as thats what we use for all other CLIs (e.g., [here](https://github.com/0xPolygonMiden/miden-vm/blob/main/miden/src/main.rs#L13)).
2. We should keep CLI parameters as consistent as possible across different CLIs (e.g., for how we specify security, number of outputs etc.). See example [here](https://github.com/0xPolygonMiden/miden-vm/blob/main/miden/src/cli/prove.rs#L11).
3. Let's change the executable file name to something like `miden-bench` (`miden-benchmarking-cli` is way too long).
4. `miden::prove()` also includes execution time, I believe. So, to make things more clear, we should probably label it as "Execution + proving time" or something like that.
5. Would also be great to print out proof size.

Look at the benchmarking CLI code in the examples repository, likely in a `benches` or `cli` directory. Compare with the main Miden VM CLI using structopt (e.g., `miden/src/main.rs` and `miden/src/cli/prove.rs`). Update the argument parsing, rename the executable in Cargo.toml, adjust timing labels in output, and add proof size reporting. Run the benchmarks to verify changes.

Written by the indexing model from the issue text.