Update dialog: add progress bar

[nimo23]

Feature Description:

Please add a progress information (e.g. "10% completed" or better "20MB of 180MB downloaded") to the progressbar when updating:

[jfaltermeier]

In the past, we had issues where the progress reported by electron-updater was either missing or incorrect, so we chose an indeterminate progress bar. We should check if this has improved.

[jfaltermeier]

As far as I can tell, we do not enter this if case: https://github.com/electron-userland/electron-builder/blob/9b72f3deebc4daeed5781db10b57adf4dd7513ec/packages/electron-updater/src/differentialDownloader/DifferentialDownloader.ts#L134. As noted in the comment, multiple ranges are not supported, so no progress is reported.

[nimo23]

In VSCode, the progressbar shows progress state, etc. Maybe it uses a 3rd party progressbar which can be used here..