chore: update metadata to conway format

[Kammerlo]

Currently when building transaction we are building within shelley format. One example is the empty bootstrap witness.
This can be deprecated in the future and could lead to errors.
Update the transaction build or outsource it to the cardanoclientlib to avoid low level functionality.

[matiwinnetou]

@Kammerlo can you please clarify if this ticket is still valid or at least if partially invalid then mark it as done and re-create another one.