Feature request: Metrics support for AspNetCore

[hjgraca]

Use case

Using Powertools with AspNetCore minimal APIs which are a popular way to deploy .NET applications on AWS Lambda.

Solution/User Experience

• Allow the user to create an instance of metrics outside the decorator.
• Allow the user to capture cold start metrics per route
• Allow users to capture cold start on all routes through middleware

Alternative solutions

Acknowledgment

• This feature request meets Powertools for AWS Lambda (.NET) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and TypeScript