Add --ce-override flag for apiserver and ping sources

[navidshaikh]

Description

• Add --ce-override flag for apiserver, ping sources and update it for SinkBinding.
• Show ce-override extensions for apiserver and ping sources, in describe output if present.

Changes

• Updated map handling utilities, cloud events extensions builder method, flag description and related unit tests for SinkBinding
• Added --ce-override flag and unit tests for APIServer and Ping sources

Reference

Fixes #849

/lint

[knative-prow-robot]

@navidshaikh: 3 warnings.

In response to this:

Description

• Add --ce-override flag apiserver, ping sources and update it for SinkBinding.

Changes

• Updated map handling utilities, cloud events extensions builder method, flag description and related unit tests for SinkBinding
• Added --ce-override flag and unit tests for APIServer and Ping sources

Reference

Fixes #849

/lint

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[knative-metrics-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/kn/commands/source/apiserver/create.go	84.8%	83.3%	-1.5
pkg/kn/commands/source/apiserver/describe.go	82.7%	85.2%	2.6
pkg/kn/commands/source/apiserver/flags.go	70.0%	70.2%	0.2
pkg/kn/commands/source/apiserver/update.go	74.4%	75.5%	1.1
pkg/kn/commands/source/binding/binding.go	60.0%	57.4%	-2.6
pkg/kn/commands/source/binding/create.go	81.6%	82.1%	0.5
pkg/kn/commands/source/binding/update.go	75.6%	77.1%	1.5
pkg/kn/commands/source/ping/create.go	88.9%	87.1%	-1.8
pkg/kn/commands/source/ping/describe.go	83.7%	87.3%	3.6
pkg/kn/commands/source/ping/flags.go	56.2%	57.1%	0.9
pkg/kn/commands/source/ping/update.go	76.3%	77.3%	1.0
pkg/sources/v1alpha2/apiserver_client.go	93.2%	90.9%	-2.3
pkg/sources/v1alpha2/binding_client.go	85.9%	85.4%	-0.5
pkg/sources/v1alpha2/ping_client.go	91.4%	89.1%	-2.3
pkg/util/parsing_helper.go	88.2%	86.8%	-1.4

[rhuss]

looks good to me. In the future, we might consider extracting the common part to be reused, but for that, we should then also think about kind of a common template for kn source describe functionality.

/lgtm
/approve

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: navidshaikh, rhuss

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