Introduce a name to remember Navigator

[andremion]

This allows us to have multiple instances of navigators whenever we need them.

For example, when using multiple NavHosts:

val mainNavigator = rememberNavigator(name = "main")
val homeNavigator = rememberNavigator(name = "home")

NavHost(
    navigator = mainNavigator,
    initialRoute = "home",
)
NavHost(
    navigator = homeNavigator,
    initialRoute = "dashboard",
)

[Tlaster]

Thanks! LGTM!