Add watch filter

[njuettner]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This will introduce watch filters, which is introduced in cluster-api in version v1alpha4. This will allow running multiple controller in a Kubernetes cluster by watching different labels.

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 #

Special notes for your reviewer:

Checklist:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

Release note:

[k8s-ci-robot]

Skipping CI for Draft Pull Request.
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[k8s-ci-robot]

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[k8s-ci-robot]

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[sedefsavas]

@njuettner thanks for the PR. We already have this covered here: #2121

[k8s-ci-robot]

@njuettner: PR needs rebase.

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[njuettner]

@sedefsavas thank you 🤗