binding-agnostic e2e tests

[cyphar]

Ideally we should be able to have a set of end-to-end tests which can work with any bindings (to ensure that all bindings are working equally). The way I envision this is to have some agreed-upon CLI interface which we implement in each binding and then run the tests (using the CLI interface) on each binding we have. Having Rust versions would also be a good idea.

The easiest way would probably be to use bats.