feat(helm-chart): add ability to set pod level security context

[bryopsida]

What

Adds a new helm value app.podSecurityContext that defaults to nil. When provided it acts as a pass through allowing users to adjust the pod level securityContext.

Evidence

Template with defaults

Command used

helm template .

Output

spec:
  replicas: 1
  selector:
    matchLabels:
      app: trust-manager
  template:
    metadata:
      labels:
        app: trust-manager
        app.kubernetes.io/name: trust-manager
        helm.sh/chart: trust-manager-v0.0.0
        app.kubernetes.io/instance: release-name
        app.kubernetes.io/version: "v0.0.0"
        app.kubernetes.io/managed-by: Helm
    spec:
      serviceAccountName: trust-manager
      automountServiceAccountToken: true
      initContainers:

Template with podSecurityContext

Command used

helm template . --set app.podSecurityContext.seccompProfile.type=RuntimeDefault

Output

spec:
  replicas: 1
  selector:
    matchLabels:
      app: trust-manager
  template:
    metadata:
      labels:
        app: trust-manager
        app.kubernetes.io/name: trust-manager
        helm.sh/chart: trust-manager-v0.0.0
        app.kubernetes.io/instance: release-name
        app.kubernetes.io/version: "v0.0.0"
        app.kubernetes.io/managed-by: Helm
    spec:
      serviceAccountName: trust-manager
      automountServiceAccountToken: true
      securityContext: 
        seccompProfile:
          type: RuntimeDefault

Relates to: #147

Notes

I saw that the chart README.md is auto generated and the command to generate/update it looks to be make generate-helm-docs but this resulted in errors locally due to the detected version, is this something that needs to be updated in this PR and if so what's the best process to do so?

[cert-manager-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign joshvanl for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[cert-manager-prow]

Hi @bryopsida. Thanks for your PR.

I'm waiting for a cert-manager member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.