Display metrics exemplars in metrics table view

[JamesNK]

PR #4629 adds exemplars to plotly graph. But they're not yet available in the table view.

[samsp-msft]

What I would propose for the table view is to add a column for the spanid, title, and show them if its available for that data point.

This may need some re-thinking of the histogram representation as we just show the P50, 90, 99 values. I would love to get more insight into the values in the buckets.
The other answer would be to show just a list of the histogram values that have exemplars and show those with the spanid & title. You could have options to sort by timestamp or by value.

[JamesNK]

Design I came up with: #4629 (comment)