[PATCH] Amended Forex Service and Added Refresh Task

[vijay-kumar-ponraj]

Design

1. Amended the DummyForexService to handle the forex rates fetch
2. Added Task Scheduler to add tasks for each 4 minutes and added Forex Rates Redis Cache Refresh Job
   • Since API expects all the data to be no more than 5 minutes older, have decided to fetch it for every 4 minutes
   • Cache TTL not set intentionally to make system Available and eventually consistent, if OneFrame service takes more than a minute to return response. User might get outdated data but it won't break, if needed we can add a boolean in API response to safely avoid this response or retry immediately until it become false.