Create Task for Tekton Pipeline end to end tests

[bobcatfish]

Expected Behavior

We should be testing and releasing Pipelines with Pipelines.

We should have a Task (and related Resources) defined that we can use to:

• Run end to end tests
• Write results to gubernator

The Task

• Inputs:
  • git repo
  • cluster (which has Tekton Pipelines already deployed to it, #534)
• Outputs:
  • some kind of result info which can be passed to Create Task to update GitHub PR status #535
• Parameters:
  • some kind of gubernator endpoint info, will have to look into existing scripts to figure this out

Actual Behavior

We currently use prow and e2e-tests.sh.

Additional Info

• Actually triggering this is not in scope for this issue, it's fine to test manually (we'll be linking these together in a later issue)
• We're going to need a service account that can update GitHub PR checks

[bobcatfish]

• These days dogfooding is in full swing and most issues are in https://github.com/tektoncd/plumbing
• This is the project we are using to track our current dogfooding efforts: https://github.com/orgs/tektoncd/projects/1
• This document contains our dogfooding plans