`Keccak256` Miden stdlib bindings

Right now, using `cargo-miden` as a library to compile a project and get a `Package` back requires a fair amount of boilerplate: calling `run()`, matching on `CommandOutput::BuildCommandOutput`, then on `BuildOutput::Masm`, reading the artifact bytes from disk, and finally deserializing with `Package::read_from_bytes()`.

The compiler's own test harness already wraps this internally (`build_package()` in test-harness, `compile_rust_package()` in integration-network helpers), so the pattern is well established.

This came up while working on the [project-template](https://github.com/0xMiden/project-template) repository, where we temporarily maintain this helper to make the DevEx smoother. Ideally we extract and standardize it so every team doesn't have to reinvent the same boilerplate.

I think it would be worth exposing a simple public function on the `cargo-miden` crate that wraps this entire pipeline:

```rust
pub fn build_package(manifest_path: &Path, release: bool) -> Result
```

I'd be happy to work on implementing this.