⚠ Move arguments from Watch() & Start() to Source objects

[inteon]

⚠️ depends on #2686

This PR removes the argument pass-through that happens when starting a Source watch.
Now, the eventhandler is passed directly to the Source constructor function.
Additionally, the predicates are now passed to the handler.WithPredicates which returns a "filtered handler".

This UX change makes the setup of Sources more intuitive, makes it much easier to create a custom Source and makes Sources easier to reason about.

[sbueringer]

@inteon Are you still interested in this PR?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: inteon
Once this PR has been reviewed and has the lgtm label, please assign fillzpp for approval. For more information see the Kubernetes Code Review Process.

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

Needs approval from an approver in each of these files:

• OWNERS

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

[inteon]

@sbueringer I rebased the PR.

[k8s-ci-robot]

@inteon: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-controller-runtime-apidiff	9894401	link	false	/test pull-controller-runtime-apidiff

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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/test-infra repository. I understand the commands that are listed here.

[k8s-ci-robot]

PR needs rebase.

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/test-infra repository.

[inteon]

A similar change has been merged in #2783