Update Electron to v25 or later

[daniellacosse]

In order to access Container Queries and the Popover API to build more robust interfaces, we need a more modern version of Electron. We're using Javascript and Media Queries for the moment, but those approaches have limitations.

We need to upgrade the version of Electron to v25 or later: https://www.electronjs.org/docs/latest/tutorial/electron-timelines#breaking-api-changes. The version chosen should be based on the OSes we still need to maintain support for (v25 drops support for Windows 8, for instance).

We should also consider upgrading both the Manager and the Client.