Add final balances parser

[LimpidCrypto]

High Level Overview of Change

• Add and export get_final_balances
• Add _compute_final_balance
• Export NormalizedNode
• Change BalanceChange to ComputedBalance
• Change BalanceChanges to ComputedBalances
• Generally renamed some terms (function names and args) that indicate to only deal with balance changes. Now indicating to deal with computed balances.

Context of Change

The #342 PR was splitted. For each exported function (get_balance_changes (already merged #383), get_final_balances, get_previous_balances and get_order_book_changes) there will now be a separate PR to make it easier to review. This PR adds the functionality to parse the final balances from a transaction's metadata (get_final_balances).

Type of Change

• New feature (non-breaking change which adds functionality)
• Tests (You added tests for code that already exists, or your new feature included in this PR)

Test Plan

I added tests that are testing the same transactions as get_balance_changes.

[JST5000]

Small naming changes, but logic looks good to me :)

[JST5000]

Looks good to me :)