[BE] Create Circuit Breaker for External API unavailability handling

[Eugeniosales]

Description:

Add circuit breaker pattern to updateExchangeRate microservice (#3) for handling Exchange Rates External API unavailbility in job.

Acceptance criteria:

• [x] Create a table CircuitBreaker in DynamoDB to controll state over microsservice calls
• [x] The Circuit Breaker must contain 2 states: open and closed.
• [x] Add Circuit Breaker to updateExchangeRate microsservice
• [x] Mock "New Relic" event to monitor Circuit Breaker state regarding observability issues