[FR] Show animated dots while sample and field counts are loading

[brimoor]

For consistency with other stats loading states in the App, I think the static ... that appears while field counts are loading in the App should be animated, similar to how Loading sample/label tags [...] is.

This isn't the most helpful GIF because the stats load fast, but, for larger datasets, stats could take longer and the user may wonder whether the App is "doing anything" or not:

Same goes for the sample count above the grid: