Refactor to only have one metadata model

[LimpidCrypto]

High Level Overview of Change

The last release included a duplicate of the TransactionMetadata model. I removed the one in the results module as the one in transaction is stronger typed. I added some missing fields to the model and the documentation. I also added the test of the result module and made sure it passes.

Type of Change

• Refactor (non-breaking change that only restructures code)

[e-desouza]

Closing this since dev doesn't exist anymore. Opened #153 against main — same idea, one TransactionMetadata instead of two. Also typed DeliveredAmount (handles the "unavailable" string from old partial payments), AffectedNode variants, and NFToken/MPToken fields while I was in there. Thanks for flagging the duplication originally.