Add block formatting options

[iquidus]

Add options to format blocks in various ways, eg:

Root level

{
  Type: uint (only eth based networks supported at present, type = 0)
}

More types to be added in future, e.g bitcoin, substrate, cosmos.

Per topic/stream

{
  Compact: bool (if true only include required fields [number, hash, parentHash])
  Transactions: bool (if true include transaction objects)
  Logs: bool (if true include log objects)
}