feat: Add style option to configure default group and references open state

[OEvgeny]

Fixes #

Changelog Entry

• Added collapsible activity and activity with abstract handling, in PR #5506, in PR #5513, in PR #5771, by @OEvgeny
  • Added styleOptions.partGroupDefaultOpen to configure whether part groups are open by default, defaults to true
  • Added styleOptions.referenceListDefaultOpen to configure whether references are open by default, defaults to true
  • In the Fluent theme "copilot" variant, part groups and references now default to closed

Description

Adds a new style options referenceListDefaultOpen and partGroupDefaultOpen that controls whether references and/or collapsible "part" activity groups start open or closed. Default to open, preserving existing behavior. The Fluent theme "copilot" variant overrides this to closed/collapsed.

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• I have added tests and executed them locally
• I have updated CHANGELOG.md
• I have updated documentation

[OEvgeny]

@copilot update the test files related to the following files adding "When (copilot): opening the group" action after the first of activities in the group lands and before the snapshot is taken. The different groups can be distinguished by isPartOf.@id. If these ids don't match, this means the messages belong to different groups.

__tests__/html2/attachment/adaptiveCard/custom.copilot.html
__tests__/html2/part-grouping/copilot.dark.html
__tests__/html2/part-grouping/copilot.html
__tests__/html2/part-grouping/folded.copilot.html
__tests__/html2/part-grouping/folded.copilot.dark.html

The code to toggle the first group on the page is:

      await host.click(document.querySelector('.collapsible-grouping__toggle'));

[Copilot]

@OEvgeny I've opened a new pull request, #5772, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

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[Copilot]

Pull request overview

Copilot reviewed 17 out of 34 changed files in this pull request and generated 2 comments.

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