Add support for ALB alarms and dashboard

[direnakkoc]

Description

Add support for ALB alarms and dashboard for the metrics are

• HTTPCode_ELB_5XX_Count
• RejectedConnectionCount
• HTTPCode_Target_5XX_Count
• UnHealthyHostCount
• LambdaInternalError
• LambdaUserError

Motivation and Context

• HTTPCode_ELB_5XX_Count- The number of HTTP 5XX server error codes that originate from the load balancer. This count does not include any response codes generated by the targets.
• RejectedConnectionCount- The number of connections that were rejected because the load balancer had reached its maximum number of connections.
• HTTPCode_Target_5XX_Count- The number of HTTP response codes generated by the targets. This does not include any response codes generated by the load balancer.
• UnHealthyHostCount- The number of targets that are considered unhealthy.
• LambdaInternalError- The number of requests to a Lambda function that failed because of an issue internal to the load balancer or AWS Lambda. To get the error reason codes, check the error_reason field of the access log.
• LambdaUserError- The number of requests to a Lambda function that failed because of an issue with the Lambda function. For example, the load balancer did not have permission to invoke the function, the load balancer received JSON from the function that is malformed or missing required fields, or the size of the request body or response exceeded the maximum size of 1 MB. To get the error reason codes, check the error_reason field of the access log.

How Has This Been Tested?

• Unit tests added

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[coveralls]

Coverage decreased (-0.1%) to 99.893% when pulling d2cfc51 on alb-metrics into 4590498 on main.