Investigate if we can support pipeline as code

[lstocchi]

A brief summary of pipeline as code so we can discuss more about it.

Pipeline as code (PAC) allows you to set up workflows (similar to github actions workflows) in a gh repo that are triggered by gh events (pull_request, push) and run on a kubernetes/openshift cluster using tekton.

So the operations a user should do to use PAC are:

1. have access to a cluster with tekton
2. set up pipeline as code on cluster and download the tkn pac cli
3. initialize the github repo where to use PAC by creating a github app (connected to the cluster through a route similar to an eventlistener afaiu) and installing it in the repo.
4. create a workflow like a pipelinerun with the events that trigger it (like pull_request, push) and add it in the .tekton folder of your project
5. every time a pull_request or push occurs, the pipelinerun is executed

My concern is that i don't see a wide usage about this. Very few ppl will work with it and it's a set and forget process. Once you set a workflow, i doubt you need to do something more, maybe you need to edit the yaml file but you can use the current tekton plugin with its code completion and push it on your gh repo.

Possible additions:

1. we can allow to download the PAC cli from the tekton extension by request and enable some action
2. list all PAC repository within cluster
3. generate a new pipelinerun (by defining event-type (pull request, push), repo url, branch, ...)
4. create new PAC repository

Demo (~10min)
https://www.youtube.com/watch?v=ytm3brml8is&ab_channel=ChmouelBoudjnah%28RedHat%29

WDYT? @jeffmaury @mohitsuman @sudhirverma