feat: install providers in system namespace

[robertgraeff]

What this PR does / why we need it:

For each provider, the openmcp-operator creates/updates certain objects (Job, Deployment, ServiceAccount, Role(Binding), ClusterRole(Binding)). This pull request changes the names and namespaces of these objects. The goal is to have all namespaced resources in a common namespace, namely the system namespace of the openmcp-operator itself — usually openmcp-system. Previously, each provider had its own namespace.

Advantages

Pull secrets can be created in one namespace, which is easier for the operator.
Moreover, providers can share pull secrets.

Naming Scheme

Object names for the cluster provider gardener:

                          NEW NAMESPACE  / NAME                 OLD NAMESPACE / NAME
Namespaced objects:       openmcp-system / cp-gardener-init     cp-gardener   / gardener-init
                          openmcp-system / cp-gardener          cp-gardener   / gardener

                          NEW NAME                              OLD NAME
Cluster-scoped objects:   openmcp.cloud:cp-gardener-init        cp-gardener:gardener-init
                          openmcp.cloud:cp-gardener             cp-gardener:gardener

Prefixes: cp- for cluster providers, sp- for service providers, ps- for platform services.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

- Install all providers in a common namespace "openmcp-system"