Add display of latest height and time

[cronokirby]

This adds a section with the latest block height and time.

For formatting the timestamp, I think using a UTC based ISO string is the simplest and most robust way, since it's completely unambiguous and eminently copy-able.

[hdevalence]

An approach I used in the LP position page that I liked was to have the time displayed in local time (according to the browser) but put the UTC time in a Tooltip component (so that the difference is clear). The problem with a UTC time is that the user has to think about conversion from their local time to UTC (unless they are the very rare person that lives in UTC).

One thing that would be good -- probably more important ux -- would be to have a client-side check, once, on page load that the time is within some threshold of the current time (say, 30s). If not, there should be some kind of warning that the data might be stale.

[conorsch]

The pd node status page displays in local timezone:

which is pretty cool and would be nice to have here, too. Adding a "stale" warning is probably the best way to inform the user about old data, but I'm not sure how to approach there. On the node status page, we check for catching_up=false and update a widget based on that. I'm surprised that the UI toolkit https://ui.penumbra.zone doesn't have a convenient helper for warning bars; maybe ping the web team about that?

[cronokirby]

Pushed a change to have a localized time, as well as a UTC time on hover

[hdevalence]

Adding a "stale" warning is probably the best way to inform the user about old data, but I'm not sure how to approach there.

I think the way to do it is to check that (when loaded) the timestamp is not too old.

But having the date is enough to solve the problem we were facing about stale data.