Add kafkaSource saslType, e2e tests for auth (tls and sasl512)

[lberk]

knative-sandbox/eventing-kafka#237 backport

• Add kafkasource SASL Type

• Add unit tests for NewConfig in source client

• wip, Add tests, lifecycle, e2e test

• Fix v1alpha1 conversion, tests

• Refactor tests

• Change kafkabinding sasltype json to 'Type'

• Rework test call structure

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[lberk]

action failures seem to be unrelated to the actual PR

[knative-metrics-robot]

The following is the coverage report on the affected files. Say /test pull-knative-eventing-contrib-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
kafka/client.go	Do not exist	75.0%
kafka/source/pkg/apis/bindings/v1alpha1/kafka_conversion.go	Do not exist	85.7%
kafka/source/pkg/apis/bindings/v1alpha1/kafka_lifecycle.go	Do not exist	57.1%
kafka/source/pkg/apis/bindings/v1alpha1/kafka_types.go	Do not exist	100.0%
kafka/source/pkg/apis/bindings/v1beta1/kafka_lifecycle.go	Do not exist	57.1%
kafka/source/pkg/apis/bindings/v1beta1/kafka_types.go	Do not exist	100.0%
kafka/source/pkg/reconciler/source/resources/receive_adapter.go	Do not exist	100.0%

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lberk, matzew

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Needs approval from an approver in each of these files: - ~~[kafka/OWNERS](https://github.com/knative/eventing-contrib/blob/release-0.18/kafka/OWNERS)~~ [lberk,matzew] - ~~[test/OWNERS](https://github.com/knative/eventing-contrib/blob/release-0.18/test/OWNERS)~~ [lberk,matzew] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment