Expand the set of doneOn clauses available to walkthrough steps

[JacksonKearl]

Currently vscode only allows a step to be doneOn a command having been executed. This should be expanded to support:

• A link being opened (via a walkthrough)
• A view having become visible
• A setting having been modified
• An extension being installed
• A context key being set
• A script (in core) explicitly checking the item off
• The item being selected

Maybe more?

cc @digitarald

[digitarald]

Given how flexible context keys are, that list looks good!

[digitarald]

For C++, clauses for launch.json and tasks.json set up. Potentially looking at specific types of entries.

[JacksonKearl]

Couple changes in tomorrows insiders:

• doneOn is deprecated in favor of new "completionEvents", doneOn will still work the same, but completionEvents are preferred going forward (this mirrors activationEvents)
• by default, with no doneOn or completionEvents set, the step will be checked when any of its buttons are pressed (links or commands)
  • if the step has no buttons, it will be checked when it's selected
• completionEvents accepts entries in the format:
  'onCommand:${1:commandId}'
  'onLink:${2:linkId}'
  'extensionInstalled:${3:extensionId}'
  'stepSelected'

See JacksonKearl/md-to-html@4c477ea for an example conversion

[JacksonKearl]

Verify by playing with the sample https://github.com/microsoft/vscode-extension-samples/tree/main/getting-started-sample, the steps use these completion events.

[alexr00]

I can't get onLink to work:

					{
						"id": "openlink",
						"title": "Open Link",
						"description": "This step will open a link and check off.\n[Open Link](http://bing.com)",
						"media": {
							"image": "media/image.png",
							"altText": "Empty image"
						},
						"completionEvents": [
							"onLink:http://bing.com"
						]
					}

[alexr00]

Also, onSettingChanged causes steps to always show as complete, even when a setting has never been touched.
Never mind, this one is working.

[alexr00]

A script (in core) explicitly checking the item off

How should this one be tested?

[JacksonKearl]

How should this one be tested?

That's there to enable checking off on settings sync being activated. If you see

when settings sync is activate, it is working as intended.

[meganrogge]

@alexr00 did you verify this or what are the items you didn't get to? I will do those.

[alexr00]

onLink needs to be verified.
This one also needs to be verified: #122570 (comment).

Everything else has been verified.