Escape label names when writing to disk.

[dlorenc]

Changes

Github/other providers allow labels to contain special characters like /. These
cannot easily be represented as filenames. This commit URL encodes these label
keys, which should provide a safe mechanism for writing these names as files.

I've been unable to find documentation containing an exhaustive list of characters
allowed in labels, but this change works with everything in the Tekton repos.

This PR also includes a sample YAML that ensures a Tekton PR has been approved, which
caught this issue.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes tests (if functionality changed/added)
• Includes docs (if user facing)
• Commit messages follow commit message best practices

Reviewer Notes

Release Notes

Describe any user facing changes here, or delete this block.

PR filenames are URL-escaped before being written to disk.

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
cmd/pullrequest-init/disk.go	74.8%	73.1%	-1.6

[vdemeester]

/cc @dibyom @bobcatfish
We need this for 0.6 too 👼

[vdemeester]

/lgtm

[bobcatfish]

Awesome!! I'm especially excited to have an example for this now too :D My only feedback is a quick plug for maybe adding a focused unit test or two, and a comment, but nothing major

[bobcatfish]

/hold

[dlorenc]

Awesome!! I'm especially excited to have an example for this now too :D My only feedback is a quick plug for maybe adding a focused unit test or two, and a comment, but nothing major

Ready!

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
cmd/pullrequest-init/disk.go	74.8%	75.9%	1.2

[dibyom]

/lgtm
/hold cancel

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dibyom, dlorenc

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Needs approval from an approver in each of these files:

• OWNERS [dibyom,dlorenc]

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