Map out input and output data structures for CLI

[debnil]

After outlining the individual commands, we should think about the data transformation that this CLI tool will do. Specifically, how are the data structures from the ingestion system transformed to the outputs sent to BigQuery? Investigating the former will build familiarity with the ingestion system. It's also likely more technically complex than the latter, which will most likely be a basic serialization/deserialization using an appropriate existing framework.

So, with that in mind, here's a checklist of the different data structures to track. In comments on this issue, you should indicate (1) which function from the ingestion system's ledgerbackend package you would call in implementation; (2) the data structure that that results in; and (3) the struct you eventually want to output to BQ. This will also help us figure out which command-line tools have more direct implementations from the ingestion system, and which require more work.

• accounts (Map out account input and output data structures for CLI #23)
• assets (Map out asset input and output data structures for CLI #42)
• ledgers (Map out ledger input and output data structures for CLI #24)
• offers (Map out offer input and output data structures for CLI #25)
• operations (Map out operations input and output data structures for CLI #26)
• trades (Map out trades input and output data structures for CLI #27)
• transactions (Map out transaction input and output data structures for CLI #43)
• trustlines (Map out trustline input and output data structures for CLI #28)