From #15730, "The dynamic client lets users consume apis which are not compiled into their binary..."

Rough TODO list is to:

• Get consensus on an interface - examine kubectl's Builder.
• Conscript runtime.Unstructured (or similar type).
• Type needs to allow easy/standardized metadata introspection.
• Make a codec supporting the type.
• Implement the client.
• Wire in to potential users; Namespace controller would be an ideal consumer.
• Replace kubectl's Builder?