Add source-kafka plugin

[daisy-ycguo]

The source-kafka plugin includes:

• feature to create a kafka source
• feature to delete a kafka source
• tests: e2e test and unit tests

[mattmoor]

Produced via:
prettier --write --prose-wrap=always $(find -name '*.md' | grep -v vendor | grep -v .github | grep -v docs/cmd/)

[mattmoor]

Produced via:
prettier --write --prose-wrap=always $(find -name '*.md' | grep -v vendor | grep -v .github | grep -v docs/cmd/)

[rhuss]

Why it is called kn-source_kafka and now kn-source-kafka ? I would expect a command like kn source kafka much like kn source apiserver or any other source.

[daisy-ycguo]

@maximilien mentioned that currently kn command, e.g. kn source, was not allowed to be extended. That is, I'm not allowed to add a subcommand kafka to kn source. But it can be changed. We could talk about that in the meeting tomorrow.

[rhuss]

Yes, if this doesn't work for kn we should fix it. Its a key feature to make built-in source, plugin source and dynamical, generic source the same for the user experience (as it really doesn't matter for the user how a source is implemented, the usage across all sources should be uniform).

[maximilien]

Yup, we need to have a way to make exception for kn source group. Will open an issue and submit a PR for this tomorrow.

[maximilien]

See issue client issue #814

[maximilien]

/test pull-knative-client-contrib-integration-tests

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: daisy-ycguo, maximilien

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[daisy-ycguo]

/test pull-knative-client-contrib-integration-tests

[daisy-ycguo]

I will close this PR, refactor it and separate into two PRs for easy review.