Add a basic grid component.

[michelle192837]

Adds a basic grid component, consisting of a grid, composed of rows, composed of a row header and cells representing statuses.

(this is experimental and not a final component, but at least some of these components should be reusable even if we switch implementations).

TODO:

• [x] Basic unit tests
• [x] Column headers
• Virtualization (only load visible DOM); follow-up PR

[google-oss-prow[bot]]

Skipping CI for Draft Pull Request. If you want CI signal for your change, please convert it to an actual PR. You can still manually trigger a test run with /test all

[google-oss-prow[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: michelle192837, sultan-duisenbay

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[sultan-duisenbay]

forgot to /hold

but wanted to mention that screenshots of the grid would also be helpful in the PR description :)

[michelle192837]

Thanks! Agree on the comments, I'll make a followup PR today 👍