Update table every second, reuse existing metric values if possible

[adamint]

We can associate rows with the underlying data's time range so that focus is not lost when the data is updated, if keyboard focus is active inside the table.

Fixes #3363

[tlmii]

I'm not very familiar with the metrics code, but this change seems reasonable for the purpose.

My only question, for future proofing, would be: Are we sure that re-using the same object will always work? That just feels a little "implementation detail". I know there's ItemKey available on the data grid. Does that achieve a similar result, and if so, might that be more reliable?

[JamesNK]

I'd like some comments about why code is needed.

[adamint]

My only question, for future proofing, would be: Are we sure that re-using the same object will always work? That just feels a little "implementation detail". I know there's ItemKey available on the data grid. Does that achieve a similar result, and if so, might that be more reliable?

Yes, that achieves the same result! I like that approach a lot more... did not realize ItemKey existed. I've updated the code to use that isntead

[JamesNK]

It fails with a runtime error...

[kvenkatrajan]

@adamint please backport for 8.0 - might be late for preview 6 - confirm.

[adamint]

/backport to release/8.0

[github-actions]

Started backporting to release/8.0: https://github.com/dotnet/aspire/actions/runs/8725980474