Adds the ability to replace webhooks on startup and configure the webhooks when creating (#525 and #532)

[ecooke-macu]

Closes #525 and Closes #532

[buehler]

I love your approach for the configuration of webhooks!

I question regarding the save method: Wouldn't it be the cleaner approach, if the save method would correctly check if the object already exists?

So instead of just using resource.Uid() is null, we could either use the try / catch with conflict exception mechanism to determine, or use the get method to search for an existing item. If it does exist -> update, if it doesn't -> create.

wdyt?

edit: I mean here: https://github.com/buehler/dotnet-operator-sdk/blob/master/src/KubeOps.KubernetesClient/KubernetesClient.cs#L116

[ecooke-macu]

I went back and forth on whether to do the way you suggested or do it in the try/catch. I can change it to your way if you would like. Wouldn't take much work.

[ecooke-macu]

I made the changes to the code to check if the validator or mutator exists and call update instead of delete/save within a try/catch.

[buehler]

Perfectly fine ;-)
Maybe the Save methods needs a change to actually search for an existing resource first. This results in two calls, but that should not bother the Kubernetes API.