Add library tests as unit tests

Use the [http-parser library tests](https://github.com/nodejs/http-parser/blob/2343fd6b5214b2ded2cdcf76de2bf60903bb90cd/test.c).
Use `uktest`, Unikraft's unit testing framework.
Check the implementation of testing for [libsodium](https://github.com/unikraft/lib-libsodium) as a model.
Try to port as many tests as you can.

**Hackathon points**: 80