[macos] Use modern version of Launch at Login

[bdlukaa]

The README says to add sindresourhus/LaunchAtLogin in the Swift Package Manager. When we open the sindresourhus/LaunchAtLogin repository, it redirects us to sindresourhus/LaunchAtLogin-Legacy, which says:

If your app targets macOS 13 or later, check out this modern version instead.

A migration guide can be found here. See sindresorhus/LaunchAtLogin-Modern for more info.

[Szanik]

Is this the way to make it work for Mac.
I am a total macOS newbie.
Installed the dependency, added the code to MainFlutterwindow and get this:

/MainFlutterWindow.swift:3:8: error: no such module 'LaunchAtLogin'

did also podinstall, and target framework macos13.