Construct library pattern for metrics

[Elad Ben-Israel]

• Productize metric code generation
  • Move the source model to L2 (from cfnspec)
  • Consider Smithy as a source format for the model
  • support static "all" metrics and update guidelines
• Add metric to cdk.IResource
• Implement and apply rule awslint:metrics-on-interface: All metric methods should be on the construct interface and not the class
• Implement and apply rule awslint:metrics-generic-method: All constructs which emit metrics should have at least a single generic "metric" method
• Implement and apply rule awslint:metrics-method-signature: Metric method signature should adhere to the rules
• Implement and apply rule awslint:metrics-static-all-generic: If there is a static all metric method, it should at least include a single "metricAll" generic method
• Implement and apply rule awslint:metrics-static-all: Verify signature of all "metricAllXxx" static methods