Refactor extracting parameters from a PipelineTask

[EmmaMunley]

Changes

This commit adds a PipelineTask method to extract all parameters and refactors
validatePipelineContextVariables using this method.

/kind cleanup

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Has Docs included if any changes are user facing
• Has Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including
  functionality, content, code)
• Has a kind label. You can add one by adding a comment on this PR that contains /kind <type>. Valid types are bug, cleanup, design, documentation, feature, flake, misc, question, tep
• Release notes block below has been updated with any user facing changes (API changes, bug fixes, changes requiring upgrade notices or deprecation warnings)
• Release notes contains the string "action required" if the change requires additional action from users switching to the new release

Release Notes

NONE

[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/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.6%	0.3
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.6%	0.3
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[JeromeJu]

suggestions for PR message:
pipelineTask(nit)
validatePipelineContextVariablesInParamValues() -> validatePipelineContextVariables since it is the caller

[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/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.5%	0.2
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.5%	0.2
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[jerop]

Thanks @EmmaMunley!

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jerop

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• pkg/apis/OWNERS [jerop]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[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/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.5%	0.2
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/apis/pipeline/v1/pipeline_types.go	96.9%	97.1%	0.2
pkg/apis/pipeline/v1/pipeline_validation.go	99.0%	99.0%	-0.1
pkg/apis/pipeline/v1beta1/pipeline_types.go	96.3%	96.5%	0.2
pkg/apis/pipeline/v1beta1/pipeline_validation.go	99.0%	99.0%	-0.1

[Yongxuanzhang]

/lgtm