CHE-15493: <username>-che as default namespace

[AndrienkoAleksandr]

Referenced issue
issue: eclipse-che/che#15493

What does this PR do?
Continue work started #137 :

• create che-workspace SA only for single workspace namespaces strategy
• check what namespace we're using for workspaces (workspaceNamespaceDefault)
  • if it is different than che-operator is deployed to, create all ClusterRoles and ClusterRoleBindings needed to create new namespaces and to create workspaces in them
  • if it is same as che-operator's namespace, create just Role and RoleBinding needed to manage workspaces in same namespace
• if oauth is enabled, just create che sa with edit, exec, view permissions.
• finalize cluster roles and cluster role bindings created by che-operator for Che server
• make working Che server property CHE_INFRA_KUBERNETES_CLUSTER__ROLE__NAME

Related pr(s)
che-incubator/chectl#469

TODO:

• test and fix permissions for k8s (currently it works for openshift)
• test with OS Oauth. PR does not grant any permissions for che sa
• check chectl
• test installation with olm

[che-bot]

Can one of the admins verify this patch?

[AndrienkoAleksandr]

CI errors on start workspaces again due image hash for che-theia: eclipse-che/che#18931

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: AndrienkoAleksandr, sparkoo, tolusha
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[openshift-ci-robot]

New changes are detected. LGTM label has been removed.

Outdated.

[sparkoo]

Just taking my approval down as today is it's 1st birthday and a lot of changed since then :)