Update bevy_main to 0.11

[eerii]

Updates the bevy-main branch to match bevy 0.11-dev. Also forwards to bevy_common_assets/main.

The most notable change is the deprecation of add_system in favor of a more general add_systems that takes the schedule as a first parameter #8079. All examples are changed to use this new function.

[NiklasEi]

Thanks 🙂