Add legacy capw labels to VirtualMachine for backward compatibility

[lubronzhan]

/kind feature

Describe the solution you'd like
The label clusterSelectorKey is added to the Machine Object. The label used to be capw.vmware.com instead of capv.vmware.com. This label, as well as nodeSelectorKey are consumed by other components.
Directly replacing the key name of the label could cause disruption during upgrade.
In order to provide a smooth upgrade experience, we should have a deprecating policy about this capw label instead of directly replacing it.

Proposal:

• Add capw and capv labels to Machine for 1 or 2 major releases.
• Remove this capw release once most customers are using new CAPV, and other component that consumes capv flag.

Updates:

• While waiting for PM's input on Deprecation process, start the code change first

Anything else you would like to add:
Cloud Provider vSphere also added capw labels . But it's for label selectors. So Cloud Provider vSphere should directly change the capw to capv label.

Environment:

• Cluster-api-provider-vsphere version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[lubronzhan]

/assign @lubronzhan

[srm09]

@aartij17 Pinging you in case Lubron needs an assist.

[srm09]

/close
Merged via #1489

[k8s-ci-robot]

@srm09: Closing this issue.

In response to this:

/close
Merged via #1489

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