add loading spinner for "Update" the file

[longshuicy]

We may need the same thing for "update" the file. This could be another task next. Thanks!

Originally posted by @longshuicy in #331 (comment)

[arunapa]

@longshuicy It seems like this is already implemented in the code here.

Also I tested in the UI -- I'm able to view it.

Do we need to change the layout or can it stay as-is?

[longshuicy]

Oh really? that's awesome. Then maybe we can close this issue