Dashboard: User-configurable Base Href in helm deployment

[lisy09]

Describe the proposal

As #168 provides the approach to configurate base href for dapr-dashboard, it is better to make this base href configurable also in helm based deployment.

modify: https://github.com/dapr/dapr/blob/master/charts/dapr/charts/dapr_dashboard/templates/dapr_dashboard_deployment.yaml

from:

...

        env:
        - name: NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
...

to:

...

        env:
        - name: NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
{{- if .Values.env.basehref }}
        - name: SERVER_BASE_HREF
           value: {{ .Values.env.basehref }}
{{- end }}
...

[yaron2]

Would you be willing to open a PR for this?