[FEATURE] Support OAuth configuration on Helm Chart

[zerowhybr]

Description

I would like configure the necessary environment variables to enable OAuth login/register when deploying the application using the Helm Chart.

Currently, the existingSecret method only supports the BETTER_AUTH_SECRET environment variable. I propose adding the other environment variables to this secret to allow for OAuth configuration and adding oauth configuration to the values.yaml file, like this:

If using built-in secrets:

oauth:
  github:
    enabled: false
    clientId: ""
    clientSecret: ""
  microsoft:
    enabled: false
    clientId: ""
    clientSecret: ""
    tenantId: ""
  generic: ""

If using existingSecret:

existingSecret: myHemmeligSecret
oauth:
  github:
    enabled: false
  microsoft:
    enabled: false

Screenshots

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Additional information

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