test: add initial unit tests

[SebastienGllmt]

This adds unit tests to the project

There were some I didn't add because it requires creating a mock utxorpc backend. The ones I did add are instead populated with static data from creating a localhost network with yaci-devkit + dolos

[SebastienGllmt]

fields equal to the default value for the data type seem to be missing if you call toJson, so I think this is probably a bug in the toJson implementation (these fields are not optional)

Either that, or these are purposely left out as a performance improvement when sending data over the wire, and there is a separate way you're support to JSONify these objects when you care about getting the full object properly