Update to Bevy 0.16 RC

[Shatur]

Straightforward migration, except:

• keybinding_menu example currently broken due to Required components behave unexpectedly for UI bevyengine/bevy#18779, but it works on main.
• @bushrat011899 previously submitted the preparation to no_std support in Prepare for Possible no_std Support #52, but for some reason it fails to compile if I enable serialize feature on Bevy.

Update: everything fixed on Bevy side with RC 4.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.03%. Comparing base (0b0e3ca) to head (2ff798a).
Report is 10 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #75   +/-   ##
=======================================
  Coverage   87.03%   87.03%           
=======================================
  Files          33       33           
  Lines        1003     1003           
=======================================
  Hits          873      873           
  Misses        130      130           

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[Shatur]

Marking as ready for review!
I'll merge this branch after Bevy 0.16 release because I'd like to draft a small release for Bevy 0.15 first.