param validation - execution status variable

[pritidesai]

Changes

Adding param validation while accessing execution status along with any other param or extra string. Updated pipelines documenting the limitation.

Also, avoiding task results validation as it follows very similar pattern with $(tasks.taskname.results.status) where
"status" being the result of some task.

Closes #3681
Closes #3692

/kind misc

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[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.6%	99.6%	0.0
pkg/substitution/substitution.go	48.1%	43.8%	-4.3

[ghost]

Might be worth adding a unit test to check that variables of form $(tasks.foo.results.status) are considered valid, to cover the case presented in #3692

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.6%	99.6%	0.0
pkg/substitution/substitution.go	48.1%	43.8%	-4.3

[pritidesai]

$(tasks.foo.results.status)

Thanks @sbwsg I have added such unit test.

@afrittoli, this PR will needs cherry picking into 0.20 🙏

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbwsg

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[GregDritschler]

looks good to me

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1beta1/pipeline_types.go	72.4%	74.2%	1.8
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.6%	99.6%	0.0
pkg/substitution/substitution.go	48.1%	43.8%	-4.3

[vdemeester]

/lgtm