Document how to setup an OIDC provider

[l0rd]

Is your enhancement related to a problem? Please describe

After the switch to the DevWorkspace and the removal of the dependency on keycloak a few issues regarding the deployment and use of an OIDC provider with Che have been created:

• is keycloak removed in eclipse-che 7.42.0 ?  #21036
• Devworkspace native auth on Kubernetes - Unauthorized! Configured service account doesn't have access #21049
• Unable to use external keycloak with Eclipse che #21229
• Need to use keycloak in che deployment #21258
• How configure keycloak as externel OIDC provider for Eclipse Che  #21282
• Eclipse Che Dashboard is not showing with error OPTIONS request to "/api/" failed, reason: "500 ". #21289
• API server is not configured with OIDC Identity Provider  #21301
• Unable to create devworkspace: Unauthorized #21325
• MicroK8S OIDC Issue #21378
• oauth-proxy container in che-gateway pod throws error while setting up eclipse-che on k8s cluster #21452
• Unable to list devworkspaces: devworkspaces.workspace.devfile.io is forbidden: User cannot list resource "devworkspaces" in API group "workspace.devfile.io" in the namespace #21477
• keycloak integration with new che helm chart #21541
• EclipseChe latest version installation on managed clusters #21556

and counting...

Describe the solution you'd like

Add a Setting up an OIDC provider section in the new Admin Guide under Preparing the installation

└──Administration Guide
	  └── Preparing the installation
		    ├── (...)
            └── Setting up an OIDC provider

There is already some good content for Rancher and GKE (probably EKS and AKS too).

Describe alternatives you've considered

Beyond documentation at some point we should to automate the OIDC configuration too.

[divinesocial]

@l0rd is the documentation available? i need guidance on setting up OIDC provider on k8s cluster (#21301). Please help

[themr0c]

Referenced in https://issues.redhat.com/browse/RHDEVDOCS-4198

[che-bot]

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