Add unit test to cover non-error cases of cbdc::nuraft_serializer::read()

[ykaravas]

This issue references a task in #3, Test Coverage / Quality Umbrella.

The cbdc::nuraft_serializer::read() does not cover non-error cases

To resolve this issue, a unit test was added to raft_test.cpp called test_raft_serializer_read which makes sure the test hash which is read from the cbdc::nuraft_serializer is in fact correct. It also moves cursor, reads and makes sure the data is once again what it should be relative to test_hash.