Convert http-USO to https-USO to enable updating

Several scripts are stuck at an old version because their downloadURL points to the http-version of USO instead of https, while `extension.greasemonkey.requireSecureUpdates` is set to true by default.

Since it is known in advance that USO is able to server content over https, we can safely convert all USO downloadURLs to the https-version.

The limitation that has been fixed affects over 6k scripts:

- [site:userscripts.org/scripts/review "@downloadURL http://userscripts.org/"](https://www.google.nl/search?q=site%3Auserscripts.org%2Fscripts%2Freview+%22%40downloadURL+http%3A%2F%2Fuserscripts.org%2F%22) - 6110 results
- [site:userscripts.org/scripts/review "@updateURL http://userscripts.org/"](https://www.google.nl/search?q=site%3Auserscripts.org%2Fscripts%2Freview+%22%40updateURL+http%3A%2F%2Fuserscripts.org%2F%22) - 13800 results.