Checkmk Werk 10651: prometheus_custom: Addition of Prometheus custom check plugin

ID: 10651 Title: prometheus_custom: Addition of Prometheus custom check plugin Component: Checks & agents Level: 2 Class: New feature Version: 1.7.0i1 This commit adds the functionality of the Prometheus custom check plugin to Checkmk. It allows the user to define PromQL queries and generate services based upon the query results. The generic check also displays information should a PromQL expression return invalid or faulty results.