Tentative fix in ArcGisPortalItemReference.ts for

[jo-chemla]

Should allow handling of ArcGisPortalItemReference not only served by ArcGIS Enterprise Portals but also ArcGIS Online “Experience Builder

See reference here
#4937 (comment)

What this PR does

Fixes #4937

WIP this is just an attempt at fixing error described in linked comment.

Test me

Checklist

• There are unit tests to verify my changes are correct or unit tests aren't applicable (if so, write quick reason why unit tests don't exist)
• I've updated relevant documentation in doc/.
• I've updated CHANGES.md with what I changed.
• I've provided instructions in the PR description on how to test this PR.

[CLAassistant]

All committers have signed the CLA.

[jo-chemla]

I'd like to test locally my minor modification to see if the ArcgisPortalItemReference can now handle both type: Map Service like this one and type: Web Map like this one - so both ArcGIS Enterprise Portals as well as ArcGIS Online Experience Builder. I've tried running the jasmine tests, but a lot are failing for unknown reasons - no clear explanation I can see on link http://localhost:3002/SpecRunner.html

Looking at other PRs, I can see the below mention, but I would like to test in a TerriaMap with both catalogs before testing the CI build. I would also be ok to edit the spec test ArcGisPortalReferenceItemSpec.ts itself to validate my change, but again not sure how to properly run it and interpret the spec tests. Any hint would be greatly appreciated!

How should reviewers test this? (Hint: If you want to provide a test catalog item, create a Gist of its catalog JSON, add its url and your branch name to this url: http://ci.terria.io//#clean& , and then paste that in the body of this PR)

Edit: sorry should have dug deeper, just saw the mention of cloning-and-building and more importantly, yarn workspaces in development-environment, should have everything there!