#3625 Update 'no screen reader for custom activity middleware' warning

[corinagum]

Fixes #3625

Changelog Entry

• Fixes #3625. Update 'no screen reader for custom activity middleware' warning and add screen reader renderer documentation to ACCESSIBILITY.md, by @corinagum in PR #3689

Description

Previously, visual activity or attachment components without an accompanying screen reader renderer threw a console error in browser. This changes that error to a warning, and adds documentation on how to suppress these warnings (not recommended).

Specific Changes

• Change applyMiddleware.js screen reader console error to warning.
• Add documentation to ACCESSIBILITY.md. See ACCESSIBILITY.md for more details.
• Add more detail to various comments
• Various linting fixes

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

Review Checklist

This section is for contributors to review your work.

• Accessibility reviewed (tab order, content readability, alt text, color contrast)
• Browser and platform compatibilities reviewed
• CSS styles reviewed (minimal rules, no z-index)
• Documents reviewed (docs, samples, live demo)
• Internationalization reviewed (strings, unit formatting)
• package.json and package-lock.json reviewed
• Security reviewed (no data URIs, check for nonce leak)
• Tests reviewed (coverage, legitimacy)

[corinagum]

@amal-khalaf technically, there should be no visual behavioral change, but the test snapshot at packages/bundle/src/adaptiveCards/AttachmentForScreenReader/AdaptiveCardAttachment.js was incorrect. I verified that the new snapshot is correct behavior with compulim. Very weird that this test was passing before.

[compulim]

Seems something wrong with the logic.

That code path only runs in Safari (quirks) and not in tests. So it won't catch in our CI pipeline.