[Accessibility]: Tables in code excerpts should use headers for line numbers

[limitedmage]

Audit type

ARC Toolkit

User journey audit issue

https://github.com/sourcegraph/sourcegraph/issues/34190

Problem description

ArcToolkit says the tables used for search results are confusing because a11y tools can't tell if the table is tabular data or used for layout purposes. We need to clarify this.

Expected behavior

The table should switch the line numbers from being <td> to <th>. This will clarify that this is indeed a table with tabular data. ArcToolkit should not show alerts about tables.

Additional details

No response

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Owner

This issue will be fixed by GitStart. I have assigned the label 'gitstart' and added the assignee 'gitstart-sourcegraph'.

/cc @lguychard

[gitstart-app]

Here is the GitStart Ticket for this issue: https://app.gitstart.com/clients/sourcegraph/tickets/SG-43144