fix: a11y-SR row count announcement in DataTable with expandable rows

[2nikhiltom]

Closes #16813

Screen reader incorrectly counts expandable content as rows. For a table with 1 header row and 6 data rows (total 7 rows), it announces additional rows by including the hidden expandable content.

Quick Question

Current fix uses aria-labels in storybook examples, but baking it into the component with a new prop like a rowCount would make it more semantic (uses proper aria-rowcount) and it will be part of component's accessibility

Changelog

New

added aria-expanded and aria-hidden to correctly announce 7 rows

Testing / Reviewing

open deploy preview and visit datatable with expandable row variants and verify correct no of rows and column are announced for the Table

[netlify]

✅ Deploy Preview for v11-carbon-web-components ready!

Name	Link
🔨 Latest commit	6a23b0e
🔍 Latest deploy log	https://app.netlify.com/sites/v11-carbon-web-components/deploys/679a1e664803050008804f7e
😎 Deploy Preview	https://deploy-preview-18457--v11-carbon-web-components.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for carbon-elements ready!

Name	Link
🔨 Latest commit	6a23b0e
🔍 Latest deploy log	https://app.netlify.com/sites/carbon-elements/deploys/679a1e66ac1fe80008873763
😎 Deploy Preview	https://deploy-preview-18457--carbon-elements.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for v11-carbon-react ready!

Name	Link
🔨 Latest commit	6a23b0e
🔍 Latest deploy log	https://app.netlify.com/sites/v11-carbon-react/deploys/679a1e662e94a00008efe4be
😎 Deploy Preview	https://deploy-preview-18457--v11-carbon-react.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.16%. Comparing base (5a0348c) to head (2ddc841).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #18457   +/-   ##
=======================================
  Coverage   84.16%   84.16%           
=======================================
  Files         408      408           
  Lines       14449    14449           
  Branches     4696     4666   -30     
=======================================
  Hits        12161    12161           
+ Misses       2124     2123    -1     
- Partials      164      165    +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[kennylam]

Adding it to the stories only solves it for the examples, but not for adopters unless they apply the same fixes on their end. Also I think using aria-rowcount would still announce the hidden rows since its purpose is to announce total rows in a table regardless of what is visible?

Maybe the best solution is to add the ARIA attributes to the components directly like you mentioned?