feat(config): add 'tpl' usage for alphaConfig.existingSecret, alphaConfig.existingConfig, config.existingConfig, podAnnotations and podLabels

[kilianpaquier]

Description

Hello Team 👋

A small PR to wrap existingConfig and existingSecret, podAnnotations and podLabels with tpl.

My use case is to create a configmap in my parent chart {{ .Release.Name }}-oauth2-proxy-custom because I want to use some .Values within the configuration (redirect_url for instance).

Addition for podAnnotations and podLabels is to add consistency with other annotations / labels tpl usage and also for the pod checksum/config.

Checklist:

• I have bumped the version in the Chart.yaml according to Semantic Versioning.
• I have updated the documentation/CHANGELOG at the bottom of the Chart.yaml
• I have signed off all my commits.
• (Optional) I have updated the Chart.lock for dependency updates
• (Optional) I have implemented helm tests for new feature flags

[kilianpaquier]

Hi @pierluigilenoci,

Thanks for the review, noted on all points, will do this tomorrow !

[kilianpaquier]

Hello @pierluigilenoci, added the suggested improvements, unit tests ran locally (hope it's still going to be fine on the CI).

EDIT: added tpl usage for podAnnotations and podLabels as it done also on deploymentAnnotations and deploymentLabels.