[RFC]: Add validator and parser in `@stdlib/bench/*` for benchmark description

### Description

This RFC proposes adding Validator and Parser for the benchmark description ( EX : `# @stdlib/blas/ddot::stacks:size=1000,ndims=2,shape=(2,500)` ) in `@stdlib/bench/*`

Until now, we have been using this descriptive format unconsciously. However, since these descriptors are crucial for visualizing the benchmarks, we need to formalize this approach by including validation and a parser that converts the description into JSON.

### Related Issues

Related issues [#6](https://github.com/stdlib-js/google-summer-of-code/issues/6)

### Questions

No.

### Other

No.

### Checklist

- [x] I have read and understood the [Code of Conduct](https://github.com/stdlib-js/stdlib/blob/develop/CODE_OF_CONDUCT.md).
- [x] Searched for existing issues and pull requests.
- [x] The issue name begins with `RFC:`.

Start by reviewing the existing @stdlib/bench/* code and the discussion in related issue #6. Define the benchmark-description format, including validation rules and the JSON representation produced by the parser; done means both capabilities are formalized for the example descriptor.

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