Feature/unit test

[satiparpar]

hey @hirotadashi , @Javadyakuza ;
Unit tests are done.
you can take a look at them and merge them.
NOTE: to run the tests update your package.json file as below:

    "test:unit": "NODE_OPTIONS=--max_old_space_size=10240 jest --runInBand --verbose ./test-bronze/chains/cardano/",
    "test:cov": "NODE_OPTIONS=--max_old_space_size=10240 jest --runInBand --coverage ./test-bronze/chains/cardano/",

and run the commands:

yarn test:unit
yarn test:cov

thanks in advance.