Determine plugin build order with a dependency graph

[maniwani]

Objective

• Fix Plugin Dependencies #69 (👈👈😎).
• Provide a different way for one plugin to spoof/substitute another (i.e. not "these plugins have the same string name").

Solution

• Think of plugin as the ECS equivalent of a crate.
• Use TypeId to differentiate plugins.
• Remove ability to override uniqueness. Only one plugin with a given TypeId to be added to an App.
  • Can maybe silence the error if two instances are configured the same.
• Defer building plugins until after they've all been added.
• Have plugins declare which plugins they depend on (or substitute) via TypeId.
• Construct a directed graph from those relationships.
• Topologically sort the graph and build plugins in that order.

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Migration Guide

TODO

[github-actions]

Example alien_cake_addict failed to run, please try running it locally and check the result.

[NthTensor]

Great work! I'm working on getting this updated and passing CI so it can be evaluated for merge. Looks largely feature complete. Were there any missing peaces I should know about?