[Feature Request] Allow Config Override

Hello Guys,

first of all thank you so much for this amazing tool! I'd like to suggest a possible advancement in the configuration: So let's say that I have a Config used by many services. For example

---
apiVersion: skaffold/v2beta29
kind: Config
metadata:
  name: postgresql
profiles:
  - name: kind-baz
    activation:
      - kubeContext: kind-baz
    deploy:
      helm:
        releases:
          - name: postgres
            repo: https://charts.bitnami.com/bitnami
            remoteChart: postgresql
            wait: true
            setValues:
              auth.enablePostgresUser: true
              auth.postgresPassword: postgres
              auth.database: foo

Usually I can include this in another config file like so

---
apiVersion: skaffold/v2beta29
kind: Config
metadata:
  name: minio
requires:
  - configs: ["postgresql"]
    path: "postgres.yaml"
profiles:
  - name: kind-baz
    activation:
      - kubeContext: kind-baz
    deploy:
      helm:
        releases:
          - name: minio
            repo: https://charts.bitnami.com/bitnami
            remoteChart: minio
            wait: true
            setValues:
              auth.rootUser: myaccesskey
              auth.rootPassword: mysecretkey
              defaultBuckets: foo-bar

This is totally fine but I believe one missing bit is the chance of overriding values in the config. Something like the following:

---
apiVersion: skaffold/v2beta29
kind: Config
metadata:
  name: minio
requires:
  - configs: ["postgresql"]
    path: "postgres.yaml"
    overrideValues:
      auth.enablePostgresUser: true
      auth.postgresPassword: bazinga
      auth.database: bazinga
profiles:
  - name: kind-baz
    activation:
      - kubeContext: kind-baz
    deploy:
      helm:
        releases:
          - name: minio
            repo: https://charts.bitnami.com/bitnami
            remoteChart: minio
            wait: true
            setValues:
              auth.rootUser: myaccesskey
              auth.rootPassword: mysecretkey
              defaultBuckets: foo-bar

In this example I've overridden all 3 values because they were already set, but I could potentially never set any default and have skaffold do the overriding job for me. In this way I could potentially fetch the base Config of postgres from another directory or anorther repository and override only what I need This would give skaffold more flexibility , unless there is another way to achieve all of this and I'm simply not aware of it. Wdyt?

Thank you