Add `labels` to Helm chart.

[hongyiweiwu01]

What would you like to be added:

Add the following fields to the Helm chart:

• master.labels
• worker.labels
• topologyUpdater.labels
• gc.labels

Why is this needed:
We sometimes want to add additional labels to pods spawned by the Helm chart, for instance to add them to the Istio mesh in ambient mode.

I'm happy to provide a PR so please let me know!

[marquiz]

@hongyiweiwu01 thank you for the idea. I think a PR is very much welcome
/cc @fmuyassarov @ArangoGutierrez

[fmuyassarov]

+1, why not

[hongyiweiwu01]

I opened a PR but it seems like it needs an approval from one of you to start the integration test. Would you mind kickstarting it? #2377