Helm chart: common labels

[MikailBag]

Motivation

Imagine a world where #19 is done, i.e. one Perforator spans across multiple Kubernetes clusters. These clusters will be definitely different in some ways, i.e. they can be located in different zones and regions. There should be a way to reflect it in labels.

Note that agent already retrieves Node topology information (usually topology.kubernetes.io/zone) and adds corresponding label. These are two distinct features: distinguishing profiles within cluster (based on cluster topology) vs distinguishing profiles across clusters (based on cluster fleet topology)

Proposed interface

Modify values as follows (naming TBD):

agent:
  config:
    commonLabels:
      region: region1

(User then needs to correctly override agent.profiler.commonLabels for each workload cluster, but it is out-of-scope for us).