code outline support

[tksst]

Is your feature request related to a problem? Please describe.

Currently code outline is not supported and nothing is displayed.

Describe the solution you'd like Display outline like Red Hat's YAML extension

[nfi-hashicorp]

I'd like to see a more tightly-integrated tree than Redhat's YAML. Actions YAML is (overly IMO) deeply nested. For example, instead of having reusable workflow inputs and outputs like this:

• on:
  • workflow_call:
    • inputs:
      • myinput:
        • value: ...
      • ...
    • outputs:
      • myoutput:
        • value: ...
      • ...

You could display that more compactly like:

• workflow_call:
  • 📥 myinput:
  • 📥 ...
  • 📤 myoutput:
  • 📤 ...

Could use some workshopping, just an idea.