Adding a loading indicator while exporting to CSV

[semoal]

When downloading large datasets, there's no visual evidence that something is happening under the hood.

Probably could be cool to add a loading status:

ui/packages/web-console/src/scenes/Result/index.tsx

Line 271 in 0469576

quest.exportQueryToCsv(sql)

p.s: i can work on this i find a free slot on our oss contributions, just feel free to give me some guidance of the UI you prefer and i can work on it ;)