Support metadata map for infrastructure to support arbitrary run contexts (e.g. application/pipeline/execution)

[ericdriggs]

Recommended implementation

• add optional flat (single level) map for infrastructure metadata as string key/value

Potential use case:

• When running spinnaker/kubernetes jobs, a project may be deployed to many applications/pipelines/executions. The cardinality is project <- application <- pipeline <- execution.
• There may be many different cardinalities for other cloud implementations
• would also allow specifying aws-region, environment, values for ENV variables, etc.. as needed

see: https://github.com/ota4j-team/open-test-reporting/blob/main/schema/src/main/resources/org/opentest4j/reporting/schema/core.xsd#L6C25-L6C39