Provide some mappings between Algod v2 and Indexer

[purestaketdb]

The current state
https://developer.algorand.org/docs/reference/rest-apis/indexer/#block
https://developer.algorand.org/docs/reference/rest-apis/algod/v2/#get-v2blocksround

The proposed state
In every case where Algod v2 and Indexer v2 have the same field BUT an entirely different encoding - provide a) a definition of the value (i..e previous block hash in Indexer is ACTUALLY a b64 string) and then a mapping back to the other. So to make Indexer previous block hash equal to the Algod v2 previous block hash one has to decode from b64 and then encode into base32.

Provide any additional context
This may be obvious to the dev team, but I cannot tell you how much time i've wasted numerous times trying to puzzle out how something is encoded and how to translate it back into something else to verify it. The indexer DB and the msgpacked blocks are other examples of this.