fix: update Refinery component templates' syntax

[robbkidd]

https://app.asana.com/0/1208469935858869/1209310061786981

Which problem is this PR solving?

• Syntax has changed some for component templates since some were written.

Short description of the changes

• Update template syntax
• Add tests

[kentquirk]

I hope you don't mind a friendly commit. I guess I could have done it as a PR but as this is still a draft, I figured it would be OK.

What I've done is change it so that if a template emits something that looks like a list: [ x, y, z ], it will take it apart and store it as a slice. This means the YAML renderer will do the right thing.

I also changed the name and semantics of firstNonblank to firstNonZero, and made it so that if it's given a list, it uses the syntax above. I think this means that firstNonZero behaves the way we want it to even if the objects are lists instead of plain data.

But also, if we just generate a template that has square brackets around it, it will be emitted as a list when rendered to a config.