More robust handling of public parameters

I think the following code snipped it problematic, since it rules out programs with public parameters that are shorter than 32 bytes.

```rust
let public_inputs: String = if bit_length > 256 {
// The user has provided the committed values rather than the digest!
// Let's reproduce the digest using the committed values
```

It think, the best solution would be to provide a separate API function for the (probably common) use case when the actual public parameters are provided.

Locate the Rust snippet that branches on bit_length and trace the API path that receives public parameters. Define the separate API entry point for actual public parameters, then verify that values shorter than 32 bytes are accepted while the existing digest-handling behavior remains intact.

Written by the indexing model from the issue text.