Natively support probe (blackbox) monitoring (MVP)

[TheSpiritXIII]

Fixes #91.

Special thanks to @bernot-dev who collaborated with me on this feature.

This PR adds native managed probe monitoring. A few features are intentionally missing in this MVP:

• The ability to specify new blackbox-exporter modules.
• The ability to specify a custom blackbox-exporter binary/pod.
• The ability to specify authorization for endpoints.