Be able to set parent labels to limit duplication in `extraLabels`

Hello

I will be great to be able to set labels on the upper level to avoid having to duplicate them [in every `extraLabels`](https://github.com/apache/incubator-devlake-helm-chart/blob/main/charts/devlake/values.yaml#L82). For example `
app.kubernetes.io/name` as [recomended](https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/). 