Feature branch for moving to Tekton 0.16

[Tomcli]

Which issue is resolved by this Pull Request:
Resolves #304

These features will break backward compatibility, need to wait for Openshift pipeline to support Tekton 0.16 before merging.

related tasks:

• Change tekton_api_version for sdk/python compiler once Conditions are out of v1apha1 #258 Server API does not accept Tekton YAML with dependency specified by after on condition node #310 when adding beta whenExpression support - UI PR feat(ui) Update UI to account for the When expression #328
  • The new conditions are now in its own "task" to replicate how Argo defines their conditions in its own Argo "template". Please check the FEATURE readme and argo condition example for more details.
• Map Argo variables to Tekton varaibles. #78 when adding more context variables
  • List of new supported variables:

    argo -> tekton
    {{workflow.uid}} -> $(context.pipelineRun.uid)
    {{workflow.name}} -> $(context.pipelineRun.name)
    {{workflow.namespace}} -> $(context.pipelineRun.namespace)
    {{workflow.parameters.%s}} -> $(params.%s)
    

• Add task wise metadata, enabled component.yaml template information.

Description of your changes:
This is an experimental feature branch for some tekton 0.16 features. We will only merge these features when OKD openshift pipeline supports Tekton 0.16+

Environment tested:

• Python Version (use python --version): 3.7
• Tekton Version (use tkn version): 0.16.3
• Kubernetes Version (use kubectl version): 1.17
• OS (e.g. from /etc/os-release):

[kubeflow-bot]

This change is 

[animeshsingh]

/hold

[drewbutlerbb4]

I have a few comments for the conditions.

Also in _group_to_dag_template of sdk/python/kfp_tekton/compiler/compiler.py
I believe we can remove
'apiVersion': tekton_api_version,
from the template since it is no longer used.

[Tomcli]

Openshift pipeline 0.16 is available in open source, need to check which IKS openshift is supporting this version.

[Tomcli]

@ckadner do you have any comment on this PR? If not we can merge it to master since this PR has been rebased multiple times.

[ckadner]

@ckadner do you have any comment on this PR? If not we can merge it to master since this PR has been rebased multiple times.

I think this looks okay. But I see changes from other merged PRs in your PR. Did you try to rebase your PR instead of merging those changes into you PR

[Tomcli]

@ckadner do you have any comment on this PR? If not we can merge it to master since this PR has been rebased multiple times.

I think this looks okay. But I see changes from other merged PRs in your PR. Did you try to rebase your PR instead of merging those changes into you PR

At some point there were too many conflicts to rebase on each commit, so I ended up with merging it and solve all the conflicts in a single batch.

[ckadner]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ckadner, Tomcli

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[Tomcli]

if there's no more objection i will unhold this PR tomorrow morning.

[Tomcli]

/unhold