state, workers: allow for actively-managed historical state

[akirillo]

This PR tweaks the state & API code paths dependent on historical state being enabled. We allow for tracking "actively-managed historical state," i.e. historical state pertaining to objects (order metadata, tasks) which may still be updated by the relayer. Concretely, this means:

• Tasks
  • We continue streaming task status updates over websocket via both the task status and task history topics. We continue to enable the task history topic since it is a reliable source of all task status updates for a given wallet.
  • We do not write tasks to the task history table if historical state is disabled.
• Orders
  • We now allow writing to / reading from the order history table even if historical state is disabled. However, if historical state is disabled we remove orders from the table once they reach a terminal state.
  • This allows us to continue streaming order metadata updates over the associated websocket topic

Testing

• All unit tests pass
• Testing in testnet w/ historical state enabled
• Testing in testnet w/ historical state disabled - requires testnet frontend integration w/ historical state engine (hooks: historical state client order & task history hooks renegade-frontend#223)
• Parity testing w/ current frontend / historical state - requires migration to be complete