feat(apiserver): Add new API subresources/v1alpha3

[yaroslavborbat]

Description

Virtualization API Refactoring

Current State (v1alpha2) - Legacy

• subresources/v1alpha2 marked as legacy
• Will be deleted in future versions
• Current endpoint: /apis/subresources.virtualization.deckhouse.io/v1alpha2/...

New State (v1alpha3)

• Add new API subresources/v1alpha3
• Add APIVirtualMachine resource that contains all VM subresources
• New endpoint: /apis/subresources.virtualization.deckhouse.io/v1alpha3/namespaces/<namespace>/apivirtualmachines/<name>/<subresource>

deckhouse/3p-kubevirt#17

Why do we need it, and what problem does it solve?

What is the expected result?

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: core
type: feature
summary: refactor virtualization-api. Mark subresources/v1alpha2 as legacy, add subresources/v1alpha3 with APIVirtualMachine resource that contains all subresources for virtual machine