Rust Snapshot Generator

This issue supersedes https://github.com/apache/datasketches-rust/issues/10 to squash the historical discussion.

Currently, the C++/Go/Java implementations of DataSketches provide snapshot generators for sketches' serialization data.

You can check the following scripts for how their snapshots get generated:

* https://github.com/apache/datasketches-tck/blob/d363b12d/serialization/cpp/generator.py
* https://github.com/apache/datasketches-tck/blob/d363b12d/serialization/go/generator.py
* https://github.com/apache/datasketches-tck/blob/d363b12d/serialization/java/generator.py

We may provide a binary in datasketches-rust as well to generate snapshots for supported sketches' serialization data.

I can imagine it as a local workspace member depending on `datasketches` and we will have a `cargo x` task to invoke the generator for automation. Or else, being part of the `serde_tests` but write the Rust sketch's serialization data to a specific location.

Start by comparing the referenced datasketches-tck serialization/cpp/generator.py, serialization/go/generator.py, and serialization/java/generator.py scripts. Then inspect the datasketches workspace and serde_tests to choose an entry point; done means generating snapshot serialization data for the supported Rust sketches in a defined location and making it invokable for automation.

Written by the indexing model from the issue text.