[che-auth] - use traefik plugin to set authorization header

[sparkoo]

Is your task related to a problem? Please describe.

Traefik now supports local plugin (traefik/traefik#8224 documentation is not merged yet, but PR is here traefik/plugindemo#13). We should use this instead of dedicated header-rewrite-proxy component.

Describe the solution you'd like

We can

1. use some existing plugin that can do what we need https://pilot.traefik.io/plugins
2. transform header-rewrite-proxy (https://github.com/che-incubator/header-rewrite-proxy/) into traefik plugin

Then we need to update che-operator, to not deploy header-rewrite-proxy, but instead deploy and configure traefik plugin. We also need to update traefik version first, to the version that supports this. We might wait to stable release.

Productize header-rewrite-proxy component as part of CRW https://issues.redhat.com/browse/CRW-1944 this may not be needed or in some different form. We won't need to build dockerimage

Describe alternatives you've considered

Use header-rewrite-proxy as separate component

Additional context

epic: Simplify authentication and authorization with a more flexible and lightweight approach #19182

[sparkoo]

Local traefik plugins are supported from version 2.5, to fully support this we need to update Traefik (update Traefik to 2.5 #20142). For development, it is easy to set traefik image in CheCluster CR.

[sparkoo]

fixed, plugin lives here https://github.com/che-incubator/header-rewrite-traefik-plugin/ , che-operator implements it here eclipse-che/che-operator#938