A builder for creating test checkpoint data.
Once initialized, the builder can be used to build multiple checkpoints.
Call start_transaction to begin creating a new transaction.
Call finish_transaction to complete the current transaction and add it to the current checkpoint.
After all transactions are added, call build_checkpoint to get the final checkpoint data.
This will also increment the stored checkpoint sequence number.
Start the above process again to build the next checkpoint.
NOTE: The generated checkpoint data is not guaranteed to be semantically valid or consistent.
For instance, all object digests will be randomly set. It focuses on providing a way to generate
various shaped test data for testing purposes.
If you need to test the validity of the checkpoint data, you should use Simulacrum instead.