Prometheus integration

[SalmaElsoly]

Description:

Used Prometheus to collect some metrics:

• HTTPRequestsReceived : counts of requests received with labels method and path
• HTTPRequestLatency : records request processing time with labels method and path
• MongoDBOperationLatency: records time taken to fulfill an operation on collection with labels operation and repo
• IdenfyResponseTime: records time taken till a response is received from a request to idenfy with labels operation
• SubstrateResponseTime: records time taken till a response is received from a request to substrate with labels operation
• ServiceUpTime: tracks the total duration in seconds that the KYC has been operating
• InternalServerErrorRate: records the numbers of failed request due to internal service errors with label method and path
• MongoDBOperationsError : records the numbers of failed operations from db with labels operation and repo

Related Issue:

#16 (comment)

Changes:

• internal/clients/idenfy/idenfy.go
• internal/clients/substrate/substrate.go
• internal/handlers/handlers.go
• internal/metrics/metrics.go
• internal/server/server.go
• internal/repository/verification_repository.go
• internal/repository/token_repository.go
• internal/middleware/middleware_test.go