Introduce chainsaw as e2e testing framework

[abaguas]

As stated in #1660, the terratest setup is quite complex. When developing new features it is often necessary to tweak the e2e testing setup, and at the moment it is quite time consuming to get it right. In addition, e2e tests are slow, they take about 25 minutes to run.

In this PR I experiment with Chainsaw Kyverno, the most popular testing framework for operators. I implemented the failover playground test as a proof of concept and I believe we can move forward with more tests. Let me know your thoughts.

Analysis

Advantages:

• declarative testing allows developers to focus only on the expected outcomes, not the testing logic
• open-source framework frees up capacity since we no longer have to maintain a testing framework
• stepTemplate CRD allows reuse of steps across multiple tests
• tests run in parallel. We have a new opportunity to get parallelism right and reduce testing time
• contains all the features we need to run a test

Disadvantages:

• no loops. Running the same test for different ingress types will involve test duplication, but at least steps can be reused. Hopefully this feature will come soon.

Test logic

The test's logic is as follows:

• Create the podinfo application
• Wait until initialization is complete: the DNSEndpoint is populated on both clusters
• Fetch the expected DNS targets from the DNSEndpoint resource and compare it with the dig's results
• Delete podinfo
• Fetch the expected DNS targets from the DNSEndpoint resource and compare it with the dig's results
• Recreate podinfo
• Fetch the expected DNS targets from the DNSEndpoint resource and compare it with the dig's results