Guide for new Kogito operator developers

With a new intern and full-timer joining the cloud team soon, I thought it would be a good opportunity to write a document walking through some of the things I needed to learn as a new developer working on the operator.

I realize there exists a GUIDE_TO_KOGITO_DEVS.md that is already in the repository, but I've highlighted some of the differences between my document and the existing one:

• targets new operator developers (vs. core/runtimes developers)
• more in-depth
• goes over CLI
• uses CRC (vs. minikube)