feat: more flexibility for defining corsAllowedHeaders and oidc.issuer

[devops-42]

Description

This PR introduces the usage of the common.tplvalues.render helper function to give more flexibility when deploying the chart in multiple environments.

References

No reference yet.

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above] -> No doc section available for the deployment template
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected -> No unittests available, but tested manually

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: devops-42 (666a3cb, a2d12ac, a0a6963)
• ✅ login: jeremy-albuixech / name: Jérémy Albuixech (f257e9c)

[whoisxx]

Thank you for the PR!
Is there a specific need to use Go templates in corsAllowedOrigins or issuer, or are you suggesting it for improvement?

[devops-42]

Thank you for the PR! Is there a specific need to use Go templates in corsAllowedOrigins or issuer, or are you suggesting it for improvement?

I suggest it for improvement: We'd like to include the chart asva subchart to deploy it in different environments. Parts of the URI strings for corsAllowedOrigins and issuer may vary.
Using the Go template like proposed in this PR would simplify our deployments: We would only need to maintain one values file having templated URI strings for corsAllowedOrigins and issuer in the according configuration section. An example configuration would look like this.

values.yaml:

http:
  corsAllowedOrigins: 
     - 'http://my.cors.{{ .Values.deploy.env }}.domain.tld'
     - 'https://my.cors.{{ .Values.deploy.env }}.domain.tld'

Assuming, the chart would be deployed in a staging environment, the according part in the deployment.yaml would be rendered like this:

[...]
- name: OPENFGA_HTTP_CORS_ALLOWED_ORIGINS
  value: http://my.cors.staging.domain.tld,https://my.cors.staging.domain.tld
[...]