Spinnaker: General Unknown Kind Deployment Handler

[Rigdon]

When deploying large manifests with multiple Kinds that are unsupported by Spinnaker natively (e.g., MutatingWebhookConfiguration, CustomResourceDefinition) it can get extremely tedious defining all of these as described in https://github.com/spinnaker/clouddriver/pull/2354. This is particularly problematic when a third-party application that makes heavy use of CRDs (such as istio) changes these it means we need to carefully review them to see if anything changed and then potentially update Spinnaker's configuration and restart clouddriver to account for them.

[roboll]

We're using CRDs extensively here at Datadog, would _really_ like to see a simpler way to manage them in Spinnaker.

[mattnworb]

+1, we do the same at Spotify, both with CustomResourceDefinitions we define internally or use from the community

[lwander]

This is addressed here: https://github.com/spinnaker/clouddriver/pull/2653 for all CRDs