[Epic] Multi-namespace support for Cryostat

[ebaron]

In order to support a Cryostat installation that works across namespaces (cryostatio/cryostat#760), we'll need to make several changes to the operator. We should attempt these changes in a non-breaking way if possible. The general new architecture will be one instance of the operator for the cluster, which manages potentially multiple Cryostat installations, each with their own set of configured namespaces they may access.

Tasks:

• Tests must support multiple namespaces #506
• Support AllNamespaces install mode #502
• [Story] Add API to allow users to install a multi-namespace Cryostat #513
• Add multi-tenancy warning for ClusterCryostats #542
• Handle name collisions between APIs #524
• Document ClusterCryostat API #521
• Add Makefile targets for multi-namespace support #522
• [Bug] "Clone of x" recordings appear cryostat#760

[ebaron]

Moving #523 out of this epic.