Display one (1) disk metric

[david-crespo]

Once oxidecomputer/omicron#1348 is merged we will be able to pull a metric from the API, and we would like to display it. The endpoint is paginated and there is currently no sampling functionality that would let us constrain the result set to a reasonable max number of data points for a given time range.

If it's a small enough number of data points that we can put it in a graph, that's cool. If even short time ranges produce too many data points for us to pull them all down, then we can at least display the first page of points in a table or something.

There is actually more than one metric available. It would be cool to do a couple.