chore: Ironfish rust refactor add change

[jowparks]

Summary

Adds change notes as a method that is executed if the transaction is a miners fee (only special type of transaction that doesn't balance). The only reason this method exists is so that no change notes are added for miner fee transactions, otherwise it would always be run inside the build() method.

Testing Plan

tests pass

Documentation

Does this change require any updates to the Iron Fish Docs (ex. the RPC API
Reference)? If yes, link a
related documentation pull request for the website.

[ ] Yes

Breaking Change

Is this a breaking change? If yes, add notes below on why this is breaking and
what additional work is required, if any.

[ ] Yes

[hughy]

Should add_change_notes ever be called outside of build?

Can we add a test for the behavior of calling build incorrectly without an address for change?

[jowparks]

Should add_change_notes ever be called outside of build?

Can we add a test for the behavior of calling build incorrectly without an address for change?

Good call! It shouldn't ever be called outside of build, so I will just make the method private, also I will add a test to verify an invalid balance is returned when change notes are not passed when they should be (ie a standard transaction post where change is present)

[jowparks]

The most canonical use case of a transaction is post, which handles this case automatically. Only when you are building intermediate UnsignedTransactions do you need to worry about this.

[jowparks]

Ok so I decided the most full proof method is determining if we should add the change note based on whether the transaction is a miners fee transaction (which can be determined by the outputs). This way it is impossible to call the method incorrectly. Miners fee with a Some() change_goes_to will still succeed, just skips adding change notes.

[jowparks]

This should never be called outside of this file.