Indexer and API support for skipped/unsupported/unprocessible transactions

[pharr117]

The indexer application handles the translation between on-chain message types to our indexed, taxable dataset. This data is then returned in the CSV API.

Users have requested that we also include the concept of "skipped" transactions in the indexer and API. This would include the following 3 categories:

• Skipped transactions - transactions that were indexed but were skipped during CSV processing for whatever reason (such as non-taxable events)
• Unsupported transactions - potentially taxable transactions that were not supported at CSV generation time
• Unprocessible transactions - transactions that errored out or were not able to be processed for any reason