ability to add additional labels

[tonymayflower]

Describe the feature:
We need to add additional labels for monitoring into the daemonset as it's the case for podAnnotation.
Describe a specific use case for the feature:
Monitoring for prometheus, Service mesh ( istio), are based on the label.

PR should come from me !!

[Crazybus]

PR should come from me !!

Awesome! I just merged in the first version of the metricbeat chart in #127. Could you also add the additonal labels into it as well? The charts are very very similar so it should just be a matter of copy paste.

[tonymayflower]

cf la PR : #214

[Crazybus]

Did you also plan on porting the same change to the metricbeat chart? If not I can pick that up.