Add delete task command

[16yuki0702]

Changes

Add deleting the task feature for #193.

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• Includes tests (if functionality changed/added)
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Release Notes

you can delete task from tkn.

[tekton-robot]

Hi @16yuki0702. Thanks for your PR.

I'm waiting for a tektoncd member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[hrishin]

/ok-to-test

[tekton-robot]

The following is the coverage report on pkg/.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/task/delete.go	Do not exist	92.9%

[chmouel]

same comment as #236 (comment) @16yuki0702 any chances we can have the same as #235, defaulting to ask if we really want to delete unless -f ?

[tekton-robot]

The following is the coverage report on pkg/.
Say /test pull-tekton-cli-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/cmd/task/delete.go	Do not exist	93.3%

[16yuki0702]

/retest

[chmouel]

/lgtm

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 16yuki0702, vdemeester

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