Move from Squirrel to electron-updater

[zootella]

Change the deployment pipeline for the file manager to:

• Hide long paths from Windows in an asar file
• Do automatic updates with Electron Forge's electron-updater instead of Squirrel
• Avoid NuGet/.nupkg, which requires downloading and installing the .NET Framework
• Make it so it only takes a few minutes to deploy the file manager, and a few seconds to install it
• Generate packages for Linux

[zootella]

The documentation I'm following to make our electron app update this way is clustered around here:

https://www.electronforge.io/ https://github.com/electron-userland/electron-forge https://github.com/electron-userland https://github.com/electron-userland/electron-packager 37,084 weekly https://github.com/electron-userland/electron-builder 83,702 weekly https://www.electron.build/ https://www.electron.build/auto-update https://www.npmjs.com/package/electron-updater 28,278 weekly