Investigate: Dry-run UX when using topology mutation hooks

[jimmidyson]

https://cluster-api.sigs.k8s.io/tasks/experimental-features/runtime-sdk/implement-topology-mutation-hook.html

[dlipovetsky]

Topology dry-run came up during January 24, 2024 CAPI office hours (see https://docs.google.com/document/d/1X5_qNUvoY0Tk3BwXODWHAl72L-APM_GiA-IE4WoitYY/edit).

The general feeling is that the command is alpha, and the runtime SDK has made it very difficult to implement at all, not to mention correctly. The command is going to be deprecated now, and an issue will be open for removal. If we have use cases that become impossible without dry-run, I'd like to share raise them on that issue.