Performance issue when zoomed out

[RobertLucey]

https://github.com/conor-f/via-web/blob/main/vue/via-web/src/components/ViaMap.vue#L135

This is called too much and performance is awful when zoomed out and the table is open. Will only get worse

Mainly noticable when moving around the map by dragging

[conor-f]

Cool. This callback is every map move/update and updating the latLngBounds tries to filter the table which involves running through every visible road segment in the geojson. Potential fixes are:

1. Only show the table view above a certain zoomLevel or when the latLngBounds cover < X km^2
2. Only show a sample of the data when in the table when the latLngBounds or zoomLevel are too expansive
3. Show an API loading spinner in the table view when updating like this. It's async so it shouldn't have any performance impact for moving the map around but I'm not certain.
4. Limit the zoomLevel on the map itself so you can never get to a point where this is an issue

Definitely more solutions too. Will keep it in mind going forward.