Time-to-readiness reporting tool

[ulucinar]

We've previously defined a simple metric named time-to-readiness, which basically captures the time it takes for a managed resource to acquire the Ready=True condition from the time recored in metadata.creationTimestamp.

A standalone tool for reporting the time-to-readiness values observed on the managed resources in a cluster will help us in collecting feedback from the community and also in future performance regression tests we would like to implement in provider repositories.

We can reuse some logic already available in this PR.

We should also consider exposing this metric as a Prometheus metric (topic of a different work stream).