Add a loader to show that files are being uploaded in the import files page
Context
When you upload multiple files in the import modal, they will need a few seconds or minute to appear on the screen. During this time it's not visible to the user what is happening and they can move to another page or try to do something.
The view is like in the image above where only the 'Continue' button is being disabled and the files will appear when all are uploaded.
Proposal
Add a loading icon to show that the upload is in progress and the user should wait shortly for the files to appear.