Add HealthCheck endpoint and Prometheus endpoint

[gwendallg]

HealthCheck Endpoint :

• In RSql4Net.Sample project
  • Add Microsoft.Extensions.Diagnostics.HealthChecks package to RSql4Net.Sample project
  • Add HealthCheck definition to StartUp.cs file with result /health : 200 json { "status":"OK" }

• In RSql4Net.Sample.Tests
  • Add a new integration test in IntegrationTest.cs file ( name ShouldBeEnsureHealthCheckEndpoint )

Prometheus Endpoint :

• In RSql4Net.Sample project

  • Add prometheus-net.AspNetCore package to RSql4net.Sample project
  • Add Prometheus definition to StartUp.cs file
  • Add a prometheus-net Histogram Object in Customer to store the duration Get Request
    • name: rsql4net_sample_customer_get_duration_seconds
    • help: Histogram of RSql4Net Sample Customer get call processing durations.

• In RSql4Net.Sample.Tests

  • Add a new integration test in IntegrationTest.cs file ( name ShouldBeEnsureMetricsEndpoint )