fix: block cell nav events w internal focus queue active

[scomea]

📖 Description

Keyboard events emitted from a data grid cell when a cell's internal navigation is active can incorrectly move focus in the parent grid. Rather than rely on authors to intercept these events the cell component can prevent their propagation.

Additionally, this change adds

• a simple 'defaultCellFocusTargetCallback` function that authors can use to move focus to the first element of a cell.
• an example of a grid with cells with internal focus targets and internal nav queue
• fixes code that detects the current active element to work within shadow doms

📑 Test Plan

Current tests all work

✅ Checklist

General

• [ x] I have included a change request file using $ yarn change
• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Component-specific

• I have added a new component
• I have modified an existing component
• I have updated the definition file
• I have updated the configuration file

[vnbaaij]

Will this also target the archive-fast-elemene-v1 branch? Otherwise the fast-blazor repo can't use it...

[Ogglas]

Any update on @vnbaaij comment? Is anything more needed before this can be merged?

[scomea]

Any update on @vnbaaij comment? Is anything more needed before this can be merged?

Working with @vnbaaij on a Blazor solution that won't require porting something back, hopefully get some progress on that this weekend. JS authors can pretty easily work around this in their own implementations by catching the same events from their internal queues as this PR does, this change should make their lives easier though. Blazor authors are more constrained.

[Ogglas]

Any update on this PR @scomea?

[scomea]

Any update on this PR @scomea?

Just pinged the collaborators to get some movement on reviews.