✨ Add addon provider fleet to registry

[Danil-Grigorev]

What this PR does / why we need it:

Adds CAAPF to the registry of addon providers.

This allows to initialize provider with clusterctl init --addon=rancher-fleet for a quick-start configuration.

Addon provider Fleet provides integration point between CAPI and Fleet GitOps solution. Addon is responsible for automatic import of CAPI clusters as a Fleet Cluster, which provisions fleet-agent on matching cluster.

Aside from GitOps functionality, default configuration can be used to deploy Bundle and HelmApp resources in the child clusters matching selectors.

Here is a demo of docker cluster deployment with automatic Calico CNI helm chart installation and configuration:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[sbueringer]

I think we have to use a org prefix: https://cluster-api.sigs.k8s.io/developer/providers/contracts/clusterctl#adding-a-provider-to-clusterctl

Given that rancher-sandbox & rancher are both owned by rancher, I think rancher-fleet is fine according to our policy

[sbueringer]

Very nice, thank you!

/approve
/area clusterctl
/cherry-pick release-1.9

[k8s-infra-cherrypick-robot]

@sbueringer: once the present PR merges, I will cherry-pick it on top of release-1.9 in a new PR and assign it to you.

In response to this:

Very nice, thank you!

/approve
/area clusterctl
/cherry-pick release-1.9

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [sbueringer]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[chrischdi]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: ba1eeb1df15071503a873bc852c6babf5302a5a8

[k8s-infra-cherrypick-robot]

@sbueringer: new pull request created: #11829

In response to this:

Very nice, thank you!

/approve
/area clusterctl
/cherry-pick release-1.9

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.