v1beta2 ImageUpdateAutomation API with refactored controller

[darkowlzz]

Ready for testing and getting familiar with the new design. Still needs more manual testing and polishing.

TODO:

• [ ] Add detailed PR description about the changes.
• [ ] Add more tests and cleanup the test helpers.
• [ ] Enable fuzz test.
• [ ] Add all the details about the changes in the respective commits.
• [ ] Write v1beta2 docs.

[darkowlzz]

Closing, created the PR from my fork.