V1: Add conversion for Pipeline.Resources

[JeromeJu]

This commit adds support for Pipeline.Resources when converting between v1beta1 and v1
versions of Pipelines. This will allow us to release v1 Pipeline in a backwards compatible way,
by ensuring that v1beta1 Pipelines with Resources will have the Resources serialized into
annotations on the v1 Pipeline on conversion.

Changes

This commit adds support for Pipeline.Resources when converting between v1beta1 and v1
versions of Pipelines. This will allow us to release v1 Pipeline in a backwards compatible way,
by ensuring that v1beta1 Pipelines with Resources will have the Resources serialized into
annotations on the v1 Pipeline on conversion.

Part of #4986
/kind misc

Submitter Checklist

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

• [n/a] Has Docs included if any changes are user facing
• [n/a] 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
• [n/a] Release notes block below has been updated with any user facing changes (API changes, bug fixes, changes requiring upgrade notices or deprecation warnings)
• [n/a] 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/v1beta1/pipeline_conversion.go	95.8%	94.5%	-1.3

[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_conversion.go	95.8%	94.5%	-1.3

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lbernick

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Needs approval from an approver in each of these files:

• pkg/apis/OWNERS [lbernick]

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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_conversion.go	95.8%	94.5%	-1.3

[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_conversion.go	95.8%	94.5%	-1.3

[jerop]

/lgtm