feat: Cluster scoped workflow template

[sarabala1979]

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
• The title of the PR is (a) conventional, (b) states what changed, and (c) suffixes the related issues number. E.g. "fix(controller): Updates such and such. Fixes #1234". Creating WorkflowTemplate on a cluster level so all namespace can use it #1729
• I have written unit and/or e2e tests for my change. PRs without these are unlike to be merged.
• Optional. I've added My organization is added to the USERS.md.
• I've signed the CLA and required builds are green.

[alexec]

I've requested a few small changes - but given approval anyway to move this forward.

[simster7]

Please hold off on merging this, I'm adding some review comments.

[simster7]

This is a minor and pedantic comment, but we use different grammar with cluster/<template_name> and namespaced/<template_name>.

In my opinion it should be either:

• clustered/<template_name> and namespaced/<template_name>; or
• cluster/<template_name> and namespace/<template_name>

[sarabala1979]

I am just following Kubernetes conventions

 # either Namespaced or Cluster
  scope: Namespaced

[sarabala1979]

// ResourceScope is an enum defining the different scopes available to a custom resource
type ResourceScope string

const (
	ClusterScoped   ResourceScope = "Cluster"
	NamespaceScoped ResourceScope = "Namespaced"
)

[sarabala1979]

@jessesuen I would like to get your feedback on this before merging this PR.

[jessesuen]

Where is this GetTemplateScope method even being used?

[jessesuen]

Also, based on the name of this method, I would expect it to return a ResourceScope type of either Cluster or Namespaced, but I see it's the scope + name of the resource, which they could already get by metadata.name

Can I learn the intended use of this method?

[sarabala1979]

it is used in multiple where the controller tries to load the stored template.
https://github.com/argoproj/argo/blob/184c3653085bc8821bdcd65f5476fbe24f24b00e/workflow/templateresolution/context.go#L152
https://github.com/argoproj/argo/blob/fb74ba1ce27b96473411c2c5cfe9a86972af589e/workflow/controller/steps.go#L199

[jessesuen]

I see, I thought it was being introduced in this change, but could not find the usage in this PR. In any case, I think following kubernetes scope naming of cluster and namespaced is the right choice.

That said, I do believe it would be better to make GetTemplateScope() return a ResourceScope kind, change GetStoredTemplate() to accept both a scope and name, and then inside GetStoredTemplate(), formulate the map key based on concatenating the two with a slash.

[sarabala1979]

I agreed with you. But TemplateScope word is used across workflowtemplate implantation and workflow spec. Instead of changing one place. I would recommend adding a new function that will return templateBaseID (scope + name) and rename variable, arguments (except spec change). I would like to do it in separate PR, so, it will be easier to review.