Expose a C API

[TheMrMilchmann]

The FFI mechanisms of many languages (including Java) support calling C-like APIs to allow interfacing with native code. I believe this is a better approach than the one proposed in pemistahl/lingua#214 because it avoids the overhead of an entire WASM runtime.

[pemistahl]

Interfacing with native code in Java would mean to compile the code for each and every architecture and put all the resulting binaries in a single JAR file. Now this is what I consider overhead. Having a WASM runtime is not that much of an overhead compared to that. And it makes the project much easier to maintain.