🌱 add support for topology managed fields

[fabriziopandini]

What this PR does / why we need it:
This PR proposes a solution for ensuring the topology controller handles nicely the removal of fields from the template.

The implementation borrows the idea of managed fields from server-side apply in Kubernetes; when executing a change on templates we keep track of the fields the template expressed opinions on (provided a value).

Then, during the next reconcile on the next object, we consider all the managed fields as authoritative paths, meaning that if the corresponding value has been removed from the desired state, we enforce removal from the resulting object.

Which issue(s) this PR fixes:
Fixes #5811

[fabriziopandini]

/test pull-cluster-api-e2e-full-main

[sbueringer]

lgtm pending the following from my side:

• 🌱 add support for topology managed fields #5812 (comment)
• 🌱 add support for topology managed fields #5812 (comment) (I meant the other test)

[sbueringer]

lgtm pending squash + golangci-lint

[vincepri]

Should we consider using some sort of encoding for this annotation? The paths can be easily compressed, and we could b64 encode the output

[fabriziopandini]

I kind of like the idea of this being human readable, so was considering something like
{ kubeadmConfigSpec { clusterConfiguration { imageRepository, version }, initConfiguration { ... } } }
But this requires a little encoder/parser and I did not include in this first iteration, but I really want to sort it out before the actual release

[vincepri]

/approve
/lgtm

[k8s-ci-robot]

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