`PreviousFields` included in `DeletedNode` metadata

[mvadari]

Here is a link to the relevant docs page: https://xrpl.org/docs/references/protocol/transactions/metadata/#deletednode-fields

Here is an example of this occurring in a transaction: https://livenet.xrpl.org/transactions/424661CF1FD3675D11EC910CF161979553B6D135F9BD03E6F8D4611D88D27581/raw

If a ledger object is modified before it's deleted, some fields will still show up in PreviousFields.