Adds rubocop as a dev dep.
`rubocop -a`ed the entire codebase.

With this in place, we can `rubocop -a` our PRs without having to deal
with the changes done to unrelated work.
Break process_sdn_node into several methods.
Merge remote-tracking branch 'origin/calum/rubocop-dash-a'
Move TradeEvent to ItaTradeEvent.

[#77714604]
TradeEvent module: better org. of related classes.
Developer sees SBA Events feed.

[#77508648]
Reorganize TradeEvents::Ita specs.
Ability to index all Trade Event sources.
Consolidated Trade Events API spec.
Able to filter cons. Trade Events by sources.
TEMPORARILY disable TTL for staging.