T6949: adds blackbox exporter (#4255)
- T6949: adds blackbox exporter
- T6949: adds basic config generation
- T6949: extract shared module config options
- T6949: switch to ipv4/6 literals
- T6949: moves config file to /run
- T6949: adds dns query name option
- T6949: adds dns query type values
- T6949: adds blackbox exporter to debian/control