Test Run Export Feature Adjustment

[antonio-amjr]

The export test run feature happens to show a popup message for the user, after the operation is complete.

The thing is that the message may appear even before.
That occurs because the browser may ask for permission or the path to download the file.

The image below shows Safari asking to allow the download with the success message already in screen:

So, the question is:
Is it possible to verify the download actually started before showing the confirmation message?

[raul-marquez-csa]

Addressed in this PR:
Implements custom saveAs function with callback #9