Proposed title of this feature request

Allow SingleNamespace as a supported installation mode for the LokiStack Operator.

What is the nature and description of the request?

Currently the only supported installation mode for the LokiStack operator is
`AllNamespaces`, see

https://github.com/grafana/loki/blob/a93f38cb055c9a3f22cf07d0bd5888a0596ec5d6/operator/bundle/openshift/manifests/loki-operator.clusterserviceversion.yaml#L1828

This RFE would like to extend the supported installation modes to `SingleNamespace` or `OwnNameSpace`

Why does the customer need this? (List the business requirements)

Currently any namespace admin can try to create a LokiStack resource. This encourages end users to try to create this kind of ressources, even though the cluster admin might now want to offer this service for end users.
Cluster admin would like to have the possibility to install the LokiStack for centralized logging, without end users thinking they would be able to do the same.

An example of operator which can be installed in SingleNamespace is the Topology operator.
Creating a LVMCluster as unpriv user returns the error:
lvmclusters.lvm.topolvm.io "my-lvmcluster" is forbidden: User "manu" cannot get resource "lvmclusters" in API group "lvm.topolvm.io" in the namespace "lvm-storage

This is what we would like to have for LokiStack.

List any affected packages or components.

LokiStack ClusterServiceVersion