[Feature request] extra-data download progress reporting

[faveoled]

When building and installing a Flatpak with extra-data, no download progress is shown. The user keeps wondering if the app hanged and how long to wait for completion

[bbhtt]

You should report this to https://github.com/flatpak/flatpak-builder/issues, it just downloads the file and runs the commands in the scripts which are sometimes silenced to prevent messing up the flatpak progress bar.

[faveoled]

flatpak/flatpak-builder#589