This implements Prometheus metric integration, including metric
definition, collection, and exportation.
Actions measured include overall Manifest application, and Chart
application with sub-actions of download, deployment, and test.
Prometheus labels are included for Manifest and Chart name as
appropriate. Chart deployment also includes a label for which action
was taken (install, upgrade, noop).
For each of these actions, metrics are included for quantity of completed
and in progress attempts and failures, as well as the duration of the
attempts.
The API exposes these metrics via an endpoint, and the Armada chart
includes the appropriate pod annotations to configure Prometheus
scraping of this endpoint.
The CLI includes a --metrics-output option to define a path
in which to output the metric data.
Change-Id: Ia0837f28073d6cd8e0220ac84cdd261b32704ae4
4e0f9009a8