Fiat balance

[osteel]

Summary

This PR adds the tracking of the fiat balance.

Explanation

Since UK tax payers are to report any capital gain or loss occurred for any transaction, including crypto-to-crypto ones, the total reported capital gain or loss doesn't necessarily reflect the actual value gained or lost in fiat terms.

This PR monitors all the swap transactions where either the acquired or disposed of asset is a fiat amount, for share pooling transactions as well as NFT ones.

Since this value is for information only and isn't meant to be reported to HMRC, I didn't use Event Sourcing to keep track of its state.

There's simply a Summary "projection" (Eloquent model) that an UpdateSummary action updates. The action is called by both the SharePoolingAssetReactor and NonFungibleAssetReactor classes. A SummaryRepository class is used to retrieve the summary.

Checklist

• I have provided a summary and an explanation
• I have reviewed the PR myself and left comments to provide context
• I have covered the changes with tests as appropriate
• I have made sure static analysis and other checks are successful