chore: example program

[richard-ramos]

Create a simple program similar to https://github.com/waku-org/nwaku/tree/master/examples/cbindings and https://github.com/waku-org/go-waku/tree/master/examples/c-bindings to demonstrate the usage of the bindings

[richard-ramos]

Implemented in #99 although I'll keep the task open as we'll keep adding functions to nwaku's bindings that must be exposed in the bindings