utils: Add additional child nesting and error item support to the activity log

[MicroFish91]

Will eventually be incorporated to support this update: microsoft/vscode-azurecontainerapps#576

I wanted to figure out a convention for handling how errors get displayed in the activity log. I currently have it working like this:

1. If error suppression flag is set, don't attach any error items
2. Otherwise, if the last activity child is a fail item, try to add the caught error as a child of the existing fail item:

3. Otherwise, if last item is not a fail item, just tack the error on at the end:

Let me know if something like this makes sense.

The base branch was changed.