helm chart support for arbitrary labels and annotations

Nobody has claimed this yet.

## Feature Request

I would like the ability to add arbitrary labels and annotations to any deployment or service created by the chart

### What problem are you trying to solve?

The issue I am personally trying to solve is how to add a `cluster-autoscaler.kubernetes.io/safe-to-evict: 'false'` label to the proxy-injector so I don't have new pods potentially falling out of the service mesh during a simultaneous autoscaling event and deployment. There are many other use cases that depend on an individual's needs.

### How should the problem be solved?

What do you want to happen? Add any considered drawbacks.

Looking at `proxy-injector.yaml`, There exists the following labels spec
```
labels:
app.kubernetes.io/name: proxy-injector
app.kubernetes.io/part-of: Linkerd
app.kubernetes.io/version: {{default .Values.global.linkerdVersion .Values.global.controllerImageVersion}}
{{.Values.global.controllerComponentLabel}}: proxy-injector
{{.Values.global.controllerNamespaceLabel}}: {{.Values.global.namespace}}
```
Adding something like below would allow users of the chart to add their own arbitrary labels
```
{{- if .Values.proxy-injector.labels}}
{{ toYaml .Values.proxy-injector.labels | indent 6 }}
{{- end }}
```
This pattern can be repeated for annotations and labels across all Deployments and Services created by the chart

Start with proxy-injector.yaml and review the chart templates for each Deployment and Service it creates. Follow the existing values and toYaml pattern for labels and annotations, then verify that arbitrary user-provided metadata can be configured consistently across all chart-created resources.

Written by the indexing model from the issue text.