startup: Use inbuilt electron API for autostartup. (#859)
startup: Use inbuilt electron API for autostartup. (#859)

Switch from using the external auto-launch module to
inbuilt setLoginItemSettings for windows and macOS,
as some users reported issues on windows.

Fixes: #851.
zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-desktop,zulip/zulip-desktop