Build the back-end component for Shutter's explorer

[ylembachar]

Develop a backend service to extract data from all relevant data sources while ensuring secure data access, either by exporting the data via a JSON API or/and by querying the relevant information from the different data sources. The data we want to expose is listed in issue: https://github.com/shutter-network/shutter-explorer/issues/1

[ulope]

Notes from the Backend kick-off meeting:

• Technology: Go
• No persistence, query data live from DBs (Observer, Encrypting RPC) and / or Victoriametrics
  • ERPC optional, txs might not all originate there
  • For now query both DBs directly unless joins are necessary. If so consider Postgres foreign tables or replication. To decide while implementing.
• Caching if necessary (in-memory or Redis, etc.)
  • Mostly static data: Validators, Keypers, etc.
  • Per Block / Slot
• JSON API for now (possibly GraphQL in the future if necessary)
• Backend and Frontend both in this repo

Task order (see #1 for detailed requirements):

• Basic project setup
• Page 1 (Keyper and Validator details)
• Page 2 (Realtime data, key generation, slots)
• Page 3 (Transaction details, tx hash search)

(Individual issues TBD)