Improve UX for HLS 2.0 layers

[hrodmn]

We added the full HLS 2.0 layers in #801 but there are a few lingering UX improvements that would make for a better browsing experience. Most of the work for these improvements will probably be in veda-ui but we can track the HLS implementation of the changes in this ticket.

1. Add "zoom in to view data" popup when user is zoomed out beyond minzoom (7 for HLS layers). The Planetary Computer explorer does the same thing:

It would be extra cool to show a layer of available granule footprints for the low zoom levels! This might help people see that there is data but they need to zoom in to see it. This feature would require some additional endpoints in titiler-cmr.

2. Surface a more visible warning that data will not be available for all dates/locations because the satellites only scan an area every 2-3 days. This is mentioned in the layer descriptions but it is easy to miss them. Some kind of info popup the first time a user adds one of the layers would be a good start.