Initial support for 2.x

[robzienert]

This PR contains the baseline work to support SDK 2.x and also introduced a couple improvements for customization. All changes include:

• Updating javaoperatorsdk to 2.0.1, fabric8 to 5.11.2, spring boot to 2.5.6.
• Changed all configurations to reflect naming conventions aligning on "reconciler" over "controller"
• Added support for custom HttpClient.Factory implementations on KubernetesClient
• Made CustomResource class resolution customizable via ResourceClassResolver, with a default implementation using Spring's ResolvableType in NaiveResourceClassResolver.
• Added a destroyMethod for the Operator bean for clean application teardown.
• Now calling start as part of the Operator bean creation. Since this is totally new behavior, perhaps it should be gated by configuration?

As for NaiveResourceClassResolver, I'm not super happy with it, but it makes the most basic use case functional. I plan to spend time on a more mature implementation later when I have more time.

Closes #7

[csviri]

Thank you @robzienert . LGTM

Now calling start as part of the Operator bean creation. Since this is totally new behavior, perhaps it should be gated by configuration?

I would say not, this is something that you always want.

[csviri]

Will add CI/CD pipelines to get it to maven central.